Task lists (#4)

* Task lists implementation

* Added since annotation to newly added method/classes

README.md

@@ -38,6 +38,11 @@ compile 'ru.noties:markwon-view:1.0.0' // optional
 * * Underline (`<u>`)
 * * Strike-through (`<s>`, `<strike>`, `<del>`)
   * other inline html is rendered via (`Html.fromHtml(...)`)
+* Task lists:
+
+- [ ] Not _done_
+  - [X] **Done** with `X`
+  - [x] ~~and~~ **or** small `x`
 
 ---
 

app/src/debug/java/ru/noties/markwon/debug/DebugCheckboxDrawableView.java

@@ -0,0 +1,74 @@
+package ru.noties.markwon.debug;
+
+import android.content.Context;
+import android.content.res.TypedArray;
+import android.graphics.Canvas;
+import android.graphics.drawable.Drawable;
+import android.support.annotation.Nullable;
+import android.util.AttributeSet;
+import android.view.View;
+
+import ru.noties.markwon.R;
+import ru.noties.markwon.spans.TaskListDrawable;
+
+public class DebugCheckboxDrawableView extends View {
+
+    private Drawable drawable;
+
+    public DebugCheckboxDrawableView(Context context) {
+        super(context);
+        init(context, null);
+    }
+
+    public DebugCheckboxDrawableView(Context context, AttributeSet attrs) {
+        super(context, attrs);
+        init(context, attrs);
+    }
+
+    private void init(Context context, @Nullable AttributeSet attrs) {
+
+        int checkedColor = 0;
+        int normalColor = 0;
+        int checkMarkColor = 0;
+
+        boolean checked = false;
+
+        if (attrs != null) {
+            final TypedArray array = context.obtainStyledAttributes(attrs, R.styleable.DebugCheckboxDrawableView);
+            try {
+
+                checkedColor = array.getColor(R.styleable.DebugCheckboxDrawableView_fcdv_checkedFillColor, checkedColor);
+                normalColor = array.getColor(R.styleable.DebugCheckboxDrawableView_fcdv_normalOutlineColor, normalColor);
+                checkMarkColor = array.getColor(R.styleable.DebugCheckboxDrawableView_fcdv_checkMarkColor, checkMarkColor);
+
+                //noinspection ConstantConditions
+                checked = array.getBoolean(R.styleable.DebugCheckboxDrawableView_fcdv_checked, checked);
+            } finally {
+                array.recycle();
+            }
+        }
+
+        final TaskListDrawable drawable = new TaskListDrawable(checkedColor, normalColor, checkMarkColor);
+        final int[] state;
+        if (checked) {
+            state = new int[]{android.R.attr.state_checked};
+        } else {
+            state = new int[0];
+        }
+        drawable.setState(state);
+
+        this.drawable = drawable;
+
+        setLayerType(LAYER_TYPE_SOFTWARE, null);
+
+        setWillNotDraw(false);
+    }
+
+    @Override
+    protected void onDraw(Canvas canvas) {
+        super.onDraw(canvas);
+
+        drawable.setBounds(0, 0, getWidth(), getHeight());
+        drawable.draw(canvas);
+    }
+}

app/src/debug/res/layout/debug_checkbox.xml

@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="utf-8"?>
+<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent">
+
+    <ru.noties.markwon.debug.DebugCheckboxDrawableView
+        android:layout_width="128dip"
+        android:layout_height="128dip"
+        android:layout_gravity="center"
+        app:fcdv_checkMarkColor="#000"
+        app:fcdv_checked="true"
+        app:fcdv_checkedFillColor="#F00"
+        app:fcdv_normalOutlineColor="#ccc" />
+
+</FrameLayout>

app/src/debug/res/values/attrs.xml

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+
+    <declare-styleable name="DebugCheckboxDrawableView">
+        <attr name="fcdv_checkedFillColor" format="color" />
+        <attr name="fcdv_normalOutlineColor" format="color" />
+        <attr name="fcdv_checkMarkColor" format="color" />
+        <attr name="fcdv_checked" format="boolean" />
+    </declare-styleable>
+
+</resources>

docs/SpannableTheme.md

@@ -105,6 +105,16 @@ public Builder tableBorderWidth(@Dimension int tableBorderWidth);
 public Builder tableOddRowBackgroundColor(@ColorInt int tableOddRowBackgroundColor);
 ```
 
+#### Task lists
+
+Task lists are supported but with some limitations. First of all, task list cannot be nested
+(in a list, quote, etc). By default (if used factory method `builderWithDefaults`) TaskListDrawable
+will be used with `linkColor` as the primary color and `windowBackground` as the checkMarkColor.
+
+```java
+public Builder taskListDrawable(@NonNull Drawable taskListDrawable);
+```
+
 
 ### Contents
 

gradle.properties

@@ -6,7 +6,7 @@ org.gradle.configureondemand=true
 android.enableBuildCache=true
 android.buildCacheDir=build/pre-dex-cache
 
-VERSION_NAME=1.0.0
+VERSION_NAME=1.0.1
 
 GROUP=ru.noties
 POM_DESCRIPTION=Markwon

library/src/main/java/ru/noties/markwon/Markwon.java

@@ -15,19 +15,26 @@ import org.commonmark.parser.Parser;
 import java.util.Arrays;
 
 import ru.noties.markwon.renderer.SpannableRenderer;
+import ru.noties.markwon.tasklist.TaskListExtension;
 
-@SuppressWarnings("WeakerAccess")
+@SuppressWarnings({"WeakerAccess", "unused"})
 public abstract class Markwon {
 
     /**
      * Helper method to obtain a Parser with registered strike-through & table extensions
+     * & task lists (added in 1.0.1)
      *
      * @return a Parser instance that is supported by this library
      * @since 1.0.0
      */
+    @NonNull
     public static Parser createParser() {
         return new Parser.Builder()
-                .extensions(Arrays.asList(StrikethroughExtension.create(), TablesExtension.create()))
+                .extensions(Arrays.asList(
+                        StrikethroughExtension.create(),
+                        TablesExtension.create(),
+                        TaskListExtension.create()
+                ))
                 .build();
     }
 
@@ -91,6 +98,7 @@ public abstract class Markwon {
      * @return parsed markdown
      * @since 1.0.0
      */
+    @Nullable
     public static CharSequence markdown(@NonNull Context context, @Nullable String markdown) {
         final CharSequence out;
         if (TextUtils.isEmpty(markdown)) {
@@ -111,6 +119,7 @@ public abstract class Markwon {
      * @see SpannableConfiguration
      * @since 1.0.0
      */
+    @Nullable
     public static CharSequence markdown(@NonNull SpannableConfiguration configuration, @Nullable String markdown) {
         final CharSequence out;
         if (TextUtils.isEmpty(markdown)) {

library/src/main/java/ru/noties/markwon/renderer/SpannableMarkdownVisitor.java

@@ -14,6 +14,7 @@ import org.commonmark.node.AbstractVisitor;
 import org.commonmark.node.BlockQuote;
 import org.commonmark.node.BulletList;
 import org.commonmark.node.Code;
+import org.commonmark.node.CustomBlock;
 import org.commonmark.node.CustomNode;
 import org.commonmark.node.Emphasis;
 import org.commonmark.node.FencedCodeBlock;
@@ -51,7 +52,10 @@ import ru.noties.markwon.spans.LinkSpan;
 import ru.noties.markwon.spans.OrderedListItemSpan;
 import ru.noties.markwon.spans.StrongEmphasisSpan;
 import ru.noties.markwon.spans.TableRowSpan;
+import ru.noties.markwon.spans.TaskListSpan;
 import ru.noties.markwon.spans.ThematicBreakSpan;
+import ru.noties.markwon.tasklist.TaskListBlock;
+import ru.noties.markwon.tasklist.TaskListItem;
 
 @SuppressWarnings("WeakerAccess")
 public class SpannableMarkdownVisitor extends AbstractVisitor {
@@ -269,6 +273,22 @@ public class SpannableMarkdownVisitor extends AbstractVisitor {
         newLine();
     }
 
+    /**
+     * @since 1.0.1
+     */
+    @Override
+    public void visit(CustomBlock customBlock) {
+        if (customBlock instanceof TaskListBlock) {
+            blockQuoteIndent += 1;
+            visitChildren(customBlock);
+            blockQuoteIndent -= 1;
+            newLine();
+            builder.append('\n');
+        } else {
+            super.visit(customBlock);
+        }
+    }
+
     @Override
     public void visit(CustomNode customNode) {
 
@@ -278,6 +298,29 @@ public class SpannableMarkdownVisitor extends AbstractVisitor {
             visitChildren(customNode);
             setSpan(length, new StrikethroughSpan());
 
+        } else if (customNode instanceof TaskListItem) {
+
+            // new in 1.0.1
+
+            final TaskListItem listItem = (TaskListItem) customNode;
+
+            final int length = builder.length();
+
+            blockQuoteIndent += listItem.indent();
+
+            visitChildren(customNode);
+
+            setSpan(length, new TaskListSpan(
+                    configuration.theme(),
+                    blockQuoteIndent,
+                    length,
+                    listItem.done()
+            ));
+
+            newLine();
+
+            blockQuoteIndent -= listItem.indent();
+
         } else if (!handleTableNodes(customNode)) {
             super.visit(customNode);
         }

library/src/main/java/ru/noties/markwon/renderer/SpannableRenderer.java

@@ -8,16 +8,9 @@ import org.commonmark.node.Node;
 
 import ru.noties.markwon.SpannableConfiguration;
 
-// please note that this class does not implement Renderer in order to return CharSequence (instead of String)
 public class SpannableRenderer {
 
-    // todo
+    @Nullable
-    // * LinkDrawableSpan, that draws link whilst image is still loading (it must be clickable...)
-    // * Common interface for images (in markdown & inline-html)
-    // * util method to properly copy markdown (with lists/links, etc)
-    // * util to apply empty line height
-    // * transform relative urls to absolute ones...
-
     public CharSequence render(@NonNull SpannableConfiguration configuration, @Nullable Node node) {
         final CharSequence out;
         if (node == null) {

library/src/main/java/ru/noties/markwon/spans/SpannableTheme.java

@@ -4,44 +4,81 @@ import android.content.Context;
 import android.content.res.TypedArray;
 import android.graphics.Paint;
 import android.graphics.Typeface;
+import android.graphics.drawable.Drawable;
 import android.support.annotation.AttrRes;
 import android.support.annotation.ColorInt;
 import android.support.annotation.Dimension;
 import android.support.annotation.FloatRange;
 import android.support.annotation.IntRange;
 import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
 import android.text.TextPaint;
 import android.util.TypedValue;
 
 @SuppressWarnings("WeakerAccess")
 public class SpannableTheme {
-//
-//    // this method should be used if TextView is known beforehand
-//    // it will correctly measure the `space` char and set it as `codeMultilineMargin`
-//    // otherwise this value must be set explicitly
-//    public static SpannableTheme create(@NonNull TextView textView) {
-//        return builderWithDefaults(textView.getContext())
-//                .codeMultilineMargin((int) (textView.getPaint().measureText("\u00a0") + .5F))
-//                .build();
-//    }
 
-    // this create default theme (except for `codeMultilineMargin` property)
+    /**
+     * Factory method to obtain an instance of {@link SpannableTheme} with all values as defaults
+     *
+     * @param context Context in order to resolve defaults
+     * @return {@link SpannableTheme} instance
+     * @see #builderWithDefaults(Context)
+     * @since 1.0.0
+     */
+    @NonNull
     public static SpannableTheme create(@NonNull Context context) {
         return builderWithDefaults(context).build();
     }
 
+    /**
+     * Factory method to obtain an instance of {@link Builder}. Please note, that no default
+     * values are set. This might be useful if you require a lot of special styling that differs
+     * a lot with default one
+     *
+     * @return {@link Builder instance}
+     * @see #builderWithDefaults(Context)
+     * @see #builder(SpannableTheme)
+     * @since 1.0.0
+     */
+    @NonNull
     public static Builder builder() {
         return new Builder();
     }
 
+    /**
+     * Factory method to create a {@link Builder} instance and initialize it with values
+     * from supplied {@link SpannableTheme}
+     *
+     * @param copyFrom {@link SpannableTheme} to copy values from
+     * @return {@link Builder} instance
+     * @see #builderWithDefaults(Context)
+     * @since 1.0.0
+     */
+    @NonNull
     public static Builder builder(@NonNull SpannableTheme copyFrom) {
         return new Builder(copyFrom);
     }
 
+    /**
+     * Factory method to obtain a {@link Builder} instance initialized with default values taken
+     * from current application theme.
+     *
+     * @param context Context to obtain default styling values (colors, etc)
+     * @return {@link Builder} instance
+     * @since 1.0.0
+     */
+    @NonNull
     public static Builder builderWithDefaults(@NonNull Context context) {
+
+        // by default we will be using link color for the checkbox color
+        // & window background as a checkMark color
+        final int linkColor = resolve(context, android.R.attr.textColorLink);
+        final int backgroundColor = resolve(context, android.R.attr.colorBackground);
+
         final Dip dip = new Dip(context);
         return new Builder()
-                .linkColor(resolve(context, android.R.attr.textColorLink))
+                .linkColor(linkColor)
                 .codeMultilineMargin(dip.toPx(8))
                 .blockMargin(dip.toPx(24))
                 .blockQuoteWidth(dip.toPx(4))
@@ -49,7 +86,8 @@ public class SpannableTheme {
                 .headingBreakHeight(dip.toPx(1))
                 .thematicBreakHeight(dip.toPx(4))
                 .tableCellPadding(dip.toPx(4))
-                .tableBorderWidth(dip.toPx(1));
+                .tableBorderWidth(dip.toPx(1))
+                .taskListDrawable(new TaskListDrawable(linkColor, linkColor, backgroundColor));
     }
 
     private static int resolve(Context context, @AttrRes int attr) {
@@ -147,6 +185,10 @@ public class SpannableTheme {
     // by default paint.color * TABLE_ODD_ROW_DEF_ALPHA
     protected final int tableOddRowBackgroundColor;
 
+    // drawable that will be used to render checkbox (should be stateful)
+    // TaskListDrawable can be used
+    protected final Drawable taskListDrawable;
+
     protected SpannableTheme(@NonNull Builder builder) {
         this.linkColor = builder.linkColor;
         this.blockMargin = builder.blockMargin;
@@ -169,6 +211,7 @@ public class SpannableTheme {
         this.tableBorderColor = builder.tableBorderColor;
         this.tableBorderWidth = builder.tableBorderWidth;
         this.tableOddRowBackgroundColor = builder.tableOddRowBackgroundColor;
+        this.taskListDrawable = builder.taskListDrawable;
     }
 
 
@@ -243,10 +286,16 @@ public class SpannableTheme {
 
         // custom typeface was set
         if (codeTypeface != null) {
+
             paint.setTypeface(codeTypeface);
+
+            // please note that we won't be calculating textSize
+            // (like we do when no Typeface is provided), if it's some specific typeface
+            // we would confuse users about textSize
             if (codeTextSize != 0) {
                 paint.setTextSize(codeTextSize);
             }
+
         } else {
             paint.setTypeface(Typeface.MONOSPACE);
             final float textSize;
@@ -363,6 +412,15 @@ public class SpannableTheme {
         paint.setStyle(Paint.Style.FILL);
     }
 
+    /**
+     * @return a Drawable to be used as a checkbox indication in task lists
+     * @since 1.0.1
+     */
+    @Nullable
+    public Drawable getTaskListDrawable() {
+        return taskListDrawable;
+    }
+
     public static class Builder {
 
         private int linkColor;
@@ -386,6 +444,7 @@ public class SpannableTheme {
         private int tableBorderColor;
         private int tableBorderWidth;
         private int tableOddRowBackgroundColor;
+        private Drawable taskListDrawable;
 
         Builder() {
         }
@@ -412,119 +471,159 @@ public class SpannableTheme {
             this.tableBorderColor = theme.tableBorderColor;
             this.tableBorderWidth = theme.tableBorderWidth;
             this.tableOddRowBackgroundColor = theme.tableOddRowBackgroundColor;
+            this.taskListDrawable = theme.taskListDrawable;
         }
 
+        @NonNull
         public Builder linkColor(@ColorInt int linkColor) {
             this.linkColor = linkColor;
             return this;
         }
 
+        @NonNull
         public Builder blockMargin(@Dimension int blockMargin) {
             this.blockMargin = blockMargin;
             return this;
         }
 
+        @NonNull
         public Builder blockQuoteWidth(@Dimension int blockQuoteWidth) {
             this.blockQuoteWidth = blockQuoteWidth;
             return this;
         }
 
+        @NonNull
         public Builder blockQuoteColor(@ColorInt int blockQuoteColor) {
             this.blockQuoteColor = blockQuoteColor;
             return this;
         }
 
+        @NonNull
         public Builder listItemColor(@ColorInt int listItemColor) {
             this.listItemColor = listItemColor;
             return this;
         }
 
+        @NonNull
         public Builder bulletListItemStrokeWidth(@Dimension int bulletListItemStrokeWidth) {
             this.bulletListItemStrokeWidth = bulletListItemStrokeWidth;
             return this;
         }
 
+        @NonNull
         public Builder bulletWidth(@Dimension int bulletWidth) {
             this.bulletWidth = bulletWidth;
             return this;
         }
 
+        @NonNull
         public Builder codeTextColor(@ColorInt int codeTextColor) {
             this.codeTextColor = codeTextColor;
             return this;
         }
 
+        @NonNull
         public Builder codeBackgroundColor(@ColorInt int codeBackgroundColor) {
             this.codeBackgroundColor = codeBackgroundColor;
             return this;
         }
 
+        @NonNull
         public Builder codeMultilineMargin(@Dimension int codeMultilineMargin) {
             this.codeMultilineMargin = codeMultilineMargin;
             return this;
         }
 
+        @NonNull
         public Builder codeTypeface(@NonNull Typeface codeTypeface) {
             this.codeTypeface = codeTypeface;
             return this;
         }
 
+        @NonNull
         public Builder codeTextSize(@Dimension int codeTextSize) {
             this.codeTextSize = codeTextSize;
             return this;
         }
 
+        @NonNull
         public Builder headingBreakHeight(@Dimension int headingBreakHeight) {
             this.headingBreakHeight = headingBreakHeight;
             return this;
         }
 
+        @NonNull
         public Builder headingBreakColor(@ColorInt int headingBreakColor) {
             this.headingBreakColor = headingBreakColor;
             return this;
         }
 
+        @NonNull
         public Builder scriptTextSizeRatio(@FloatRange(from = .0F, to = Float.MAX_VALUE) float scriptTextSizeRatio) {
             this.scriptTextSizeRatio = scriptTextSizeRatio;
             return this;
         }
 
+        @NonNull
         public Builder thematicBreakColor(@ColorInt int thematicBreakColor) {
             this.thematicBreakColor = thematicBreakColor;
             return this;
         }
 
+        @NonNull
         public Builder thematicBreakHeight(@Dimension int thematicBreakHeight) {
             this.thematicBreakHeight = thematicBreakHeight;
             return this;
         }
 
+        @NonNull
         public Builder tableCellPadding(@Dimension int tableCellPadding) {
             this.tableCellPadding = tableCellPadding;
             return this;
         }
 
+        @NonNull
         public Builder tableBorderColor(@ColorInt int tableBorderColor) {
             this.tableBorderColor = tableBorderColor;
             return this;
         }
 
+        @NonNull
         public Builder tableBorderWidth(@Dimension int tableBorderWidth) {
             this.tableBorderWidth = tableBorderWidth;
             return this;
         }
 
+        @NonNull
         public Builder tableOddRowBackgroundColor(@ColorInt int tableOddRowBackgroundColor) {
             this.tableOddRowBackgroundColor = tableOddRowBackgroundColor;
             return this;
         }
 
+        /**
+         * Supplied Drawable must be stateful ({@link Drawable#isStateful()} -> true). If a task
+         * is marked as done, then this drawable will be updated with an {@code int[] { android.R.attr.state_checked }}
+         * as the state, otherwise an empty array will be used. This library provides a ready to be
+         * used Drawable: {@link TaskListDrawable}
+         *
+         * @param taskListDrawable Drawable to be used as the task list indication (checkbox)
+         * @see TaskListDrawable
+         * @since 1.0.1
+         */
+        @NonNull
+        public Builder taskListDrawable(@NonNull Drawable taskListDrawable) {
+            this.taskListDrawable = taskListDrawable;
+            return this;
+        }
+
+        @NonNull
         public SpannableTheme build() {
             return new SpannableTheme(this);
         }
     }
 
     private static class Dip {
+
         private final float density;
 
         Dip(@NonNull Context context) {

library/src/main/java/ru/noties/markwon/spans/TaskListDrawable.java

@@ -0,0 +1,180 @@
+package ru.noties.markwon.spans;
+
+import android.graphics.Canvas;
+import android.graphics.ColorFilter;
+import android.graphics.Paint;
+import android.graphics.Path;
+import android.graphics.PixelFormat;
+import android.graphics.Rect;
+import android.graphics.RectF;
+import android.graphics.drawable.Drawable;
+import android.support.annotation.ColorInt;
+import android.support.annotation.IntRange;
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+
+/**
+ * @since 1.0.1
+ */
+@SuppressWarnings("WeakerAccess")
+public class TaskListDrawable extends Drawable {
+
+    // represent ratios (not exact coordinates)
+    private static final Point POINT_0 = new Point(2.75F / 18, 8.25F / 18);
+    private static final Point POINT_1 = new Point(7.F / 18, 12.5F / 18);
+    private static final Point POINT_2 = new Point(15.25F / 18, 4.75F / 18);
+
+    private final int checkedFillColor;
+    private final int normalOutlineColor;
+
+    private final Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
+    private final RectF rectF = new RectF();
+
+    private final Paint checkMarkPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
+    private final Path checkMarkPath = new Path();
+
+    private boolean isChecked;
+
+    // unfortunately we cannot rely on TextView to be LAYER_TYPE_SOFTWARE
+    // if we could we would draw our checkMarkPath with PorterDuff.CLEAR
+    public TaskListDrawable(@ColorInt int checkedFillColor, @ColorInt int normalOutlineColor, @ColorInt int checkMarkColor) {
+        this.checkedFillColor = checkedFillColor;
+        this.normalOutlineColor = normalOutlineColor;
+
+        checkMarkPaint.setColor(checkMarkColor);
+        checkMarkPaint.setStyle(Paint.Style.STROKE);
+    }
+
+    @Override
+    protected void onBoundsChange(Rect bounds) {
+        super.onBoundsChange(bounds);
+
+        // we should exclude stroke with from final bounds (half of the strokeWidth from all sides)
+
+        // we should have square shape
+        final float min = Math.min(bounds.width(), bounds.height());
+        final float stroke = min / 8;
+
+        final float side = min - stroke;
+        rectF.set(0, 0, side, side);
+
+        paint.setStrokeWidth(stroke);
+        checkMarkPaint.setStrokeWidth(stroke);
+
+        checkMarkPath.reset();
+
+        POINT_0.moveTo(checkMarkPath, side);
+        POINT_1.lineTo(checkMarkPath, side);
+        POINT_2.lineTo(checkMarkPath, side);
+    }
+
+    @Override
+    public void draw(@NonNull Canvas canvas) {
+
+        final Paint.Style style;
+        final int color;
+
+        if (isChecked) {
+            style = Paint.Style.FILL_AND_STROKE;
+            color = checkedFillColor;
+        } else {
+            style = Paint.Style.STROKE;
+            color = normalOutlineColor;
+        }
+        paint.setStyle(style);
+        paint.setColor(color);
+
+        final Rect bounds = getBounds();
+
+        final float left = (bounds.width() - rectF.width()) / 2;
+        final float top = (bounds.height() - rectF.height()) / 2;
+
+        final float radius = rectF.width() / 8;
+
+        final int save = canvas.save();
+        try {
+
+            canvas.translate(left, top);
+
+            canvas.drawRoundRect(rectF, radius, radius, paint);
+
+            if (isChecked) {
+                canvas.drawPath(checkMarkPath, checkMarkPaint);
+            }
+        } finally {
+            canvas.restoreToCount(save);
+        }
+    }
+
+    @Override
+    public void setAlpha(@IntRange(from = 0, to = 255) int alpha) {
+        paint.setAlpha(alpha);
+    }
+
+    @Override
+    public void setColorFilter(@Nullable ColorFilter colorFilter) {
+        paint.setColorFilter(colorFilter);
+    }
+
+    @Override
+    public int getOpacity() {
+        return PixelFormat.OPAQUE;
+    }
+
+    @Override
+    public boolean isStateful() {
+        return true;
+    }
+
+    @Override
+    protected boolean onStateChange(int[] state) {
+
+        final boolean checked;
+
+        final int length = state != null
+                ? state.length
+                : 0;
+
+        if (length > 0) {
+
+            boolean inner = false;
+
+            for (int i = 0; i < length; i++) {
+                if (android.R.attr.state_checked == state[i]) {
+                    inner = true;
+                    break;
+                }
+            }
+            checked = inner;
+        } else {
+            checked = false;
+        }
+
+        final boolean result = checked != isChecked;
+        if (result) {
+            invalidateSelf();
+            isChecked = checked;
+        }
+
+        return result;
+    }
+
+    private static class Point {
+
+        final float x;
+        final float y;
+
+        Point(float x, float y) {
+            this.x = x;
+            this.y = y;
+        }
+
+        void moveTo(@NonNull Path path, float side) {
+            path.moveTo(side * x, side * y);
+        }
+
+        void lineTo(@NonNull Path path, float side) {
+            path.lineTo(side * x, side * y);
+        }
+    }
+}

library/src/main/java/ru/noties/markwon/spans/TaskListSpan.java

@@ -0,0 +1,75 @@
+package ru.noties.markwon.spans;
+
+import android.graphics.Canvas;
+import android.graphics.Paint;
+import android.graphics.drawable.Drawable;
+import android.support.annotation.NonNull;
+import android.text.Layout;
+import android.text.style.LeadingMarginSpan;
+
+/**
+ * @since 1.0.1
+ */
+public class TaskListSpan implements LeadingMarginSpan {
+
+    private final SpannableTheme theme;
+    private final int blockIndent;
+    private final int start;
+    private final boolean isDone;
+
+    public TaskListSpan(@NonNull SpannableTheme theme, int blockIndent, int start, boolean isDone) {
+        this.theme = theme;
+        this.blockIndent = blockIndent;
+        this.start = start;
+        this.isDone = isDone;
+    }
+
+    @Override
+    public int getLeadingMargin(boolean first) {
+        return theme.getBlockMargin() * blockIndent;
+    }
+
+    @Override
+    public void drawLeadingMargin(Canvas c, Paint p, int x, int dir, int top, int baseline, int bottom, CharSequence text, int start, int end, boolean first, Layout layout) {
+
+        if (this.start != start) {
+            return;
+        }
+
+        final Drawable drawable = theme.getTaskListDrawable();
+        if (drawable == null) {
+            return;
+        }
+
+        final int save = c.save();
+        try {
+
+            final int width = theme.getBlockMargin();
+            final int height = bottom - top;
+
+            final int w = (int) (width * .75F + .5F);
+            final int h = (int) (height * .75F + .5F);
+
+            drawable.setBounds(0, 0, w, h);
+
+            if (drawable.isStateful()) {
+                final int[] state;
+                if (isDone) {
+                    state = new int[]{android.R.attr.state_checked};
+                } else {
+                    state = new int[0];
+                }
+                drawable.setState(state);
+            }
+
+            final int l = (width * (blockIndent - 1)) + ((width - w) / 2);
+            final int t = top + ((height - h) / 2);
+
+            c.translate(l, t);
+            drawable.draw(c);
+
+        } finally {
+            c.restoreToCount(save);
+        }
+    }
+}

library/src/main/java/ru/noties/markwon/tasklist/TaskListBlock.java

@@ -0,0 +1,9 @@
+package ru.noties.markwon.tasklist;
+
+import org.commonmark.node.CustomBlock;
+
+/**
+ * @since 1.0.1
+ */
+public class TaskListBlock extends CustomBlock {
+}

library/src/main/java/ru/noties/markwon/tasklist/TaskListBlockParser.java

@@ -0,0 +1,150 @@
+package ru.noties.markwon.tasklist;
+
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+
+import org.commonmark.node.Block;
+import org.commonmark.parser.InlineParser;
+import org.commonmark.parser.block.AbstractBlockParser;
+import org.commonmark.parser.block.AbstractBlockParserFactory;
+import org.commonmark.parser.block.BlockContinue;
+import org.commonmark.parser.block.BlockStart;
+import org.commonmark.parser.block.MatchedBlockParser;
+import org.commonmark.parser.block.ParserState;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+/**
+ * @since 1.0.1
+ */
+@SuppressWarnings("WeakerAccess")
+class TaskListBlockParser extends AbstractBlockParser {
+
+    private static final Pattern PATTERN = Pattern.compile("\\s*-\\s+\\[(x|X|\\s)\\]\\s+(.*)");
+
+    private final TaskListBlock block = new TaskListBlock();
+
+    private final List<Item> items = new ArrayList<>(3);
+
+    private int indent = 0;
+
+    TaskListBlockParser(@NonNull String startLine, int startIndent) {
+        items.add(new Item(startLine, startIndent));
+        indent = startIndent;
+    }
+
+    @Override
+    public Block getBlock() {
+        return block;
+    }
+
+    @Override
+    public BlockContinue tryContinue(ParserState parserState) {
+
+        final BlockContinue blockContinue;
+
+        final String line = line(parserState);
+
+        final int currentIndent = parserState.getIndent();
+        if (currentIndent > indent) {
+            indent += 2;
+        } else if (currentIndent < indent && indent > 1) {
+            indent -= 2;
+        }
+
+        if (line != null
+                && line.length() > 0
+                && PATTERN.matcher(line).matches()) {
+            blockContinue = BlockContinue.atIndex(parserState.getIndex());
+        } else {
+            blockContinue = BlockContinue.finished();
+        }
+
+        return blockContinue;
+    }
+
+    @Override
+    public void addLine(CharSequence line) {
+        if (length(line) > 0) {
+            items.add(new Item(line.toString(), indent));
+        }
+    }
+
+    @Override
+    public void parseInlines(InlineParser inlineParser) {
+
+        Matcher matcher;
+
+        TaskListItem listItem;
+
+        for (Item item : items) {
+            matcher = PATTERN.matcher(item.line);
+            if (!matcher.matches()) {
+                continue;
+            }
+            listItem = new TaskListItem()
+                    .done(isDone(matcher.group(1)))
+                    .indent(item.indent / 2);
+            inlineParser.parse(matcher.group(2), listItem);
+            block.appendChild(listItem);
+        }
+    }
+
+    static class Factory extends AbstractBlockParserFactory {
+
+        @Override
+        public BlockStart tryStart(ParserState state, MatchedBlockParser matchedBlockParser) {
+
+            final String line = line(state);
+
+            if (line != null
+                    && line.length() > 0
+                    && PATTERN.matcher(line).matches()) {
+
+                final int length = line.length();
+                final int index = state.getIndex();
+                final int atIndex = index != 0
+                        ? index + (length - index)
+                        : length;
+
+                return BlockStart.of(new TaskListBlockParser(line, state.getIndent()))
+                        .atIndex(atIndex);
+            }
+
+            return BlockStart.none();
+        }
+    }
+
+    @Nullable
+    private static String line(@NonNull ParserState state) {
+        final CharSequence lineRaw = state.getLine();
+        return lineRaw != null
+                ? lineRaw.toString()
+                : null;
+    }
+
+    private static int length(@Nullable CharSequence text) {
+        return text != null
+                ? text.length()
+                : 0;
+    }
+
+    private static boolean isDone(@NonNull String value) {
+        return "X".equals(value)
+                || "x".equals(value);
+    }
+
+    private static class Item {
+
+        final String line;
+        final int indent;
+
+        Item(@NonNull String line, int indent) {
+            this.line = line;
+            this.indent = indent;
+        }
+    }
+}

library/src/main/java/ru/noties/markwon/tasklist/TaskListExtension.java

@@ -0,0 +1,21 @@
+package ru.noties.markwon.tasklist;
+
+import android.support.annotation.NonNull;
+
+import org.commonmark.parser.Parser;
+
+/**
+ * @since 1.0.1
+ */
+public class TaskListExtension implements Parser.ParserExtension {
+
+    @NonNull
+    public static TaskListExtension create() {
+        return new TaskListExtension();
+    }
+
+    @Override
+    public void extend(Parser.Builder parserBuilder) {
+        parserBuilder.customBlockParserFactory(new TaskListBlockParser.Factory());
+    }
+}

library/src/main/java/ru/noties/markwon/tasklist/TaskListItem.java

@@ -0,0 +1,31 @@
+package ru.noties.markwon.tasklist;
+
+import org.commonmark.node.CustomNode;
+
+/**
+ * @since 1.0.1
+ */
+@SuppressWarnings("WeakerAccess")
+public class TaskListItem extends CustomNode {
+
+    private boolean done;
+    private int indent;
+
+    public boolean done() {
+        return done;
+    }
+
+    public TaskListItem done(boolean done) {
+        this.done = done;
+        return this;
+    }
+
+    public int indent() {
+        return indent;
+    }
+
+    public TaskListItem indent(int indent) {
+        this.indent = indent;
+        return this;
+    }
+}