Change text-setter to use precomputed-text-compat (androix.core)

CHANGELOG.md

@@ -1,5 +1,10 @@
 # Changelog
 
+# 4.1.0-SNAPSHOT
+* Add `Markwon.TextSetter` interface to be able to use PrecomputedText/PrecomputedTextCompat
+* Add `PrecomputedTextSetterCompat` and `compileOnly` dependency on `androidx.core:core` 
+(clients must have this dependency in the classpath)
+
 # 4.0.2
 * Fix `JLatexMathPlugin` formula placeholder (cannot have line breaks) ([#149])
 * Fix `JLatexMathPlugin` to update resulting formula bounds when `fitCanvas=true` and 

build.gradle

@@ -59,6 +59,7 @@ ext {
     deps = [
             'x-annotations'           : 'androidx.annotation:annotation:1.1.0',
             'x-recycler-view'         : 'androidx.recyclerview:recyclerview:1.0.0',
+            'x-core'                  : 'androidx.core:core:1.0.2',
             'commonmark'              : "com.atlassian.commonmark:commonmark:$commonMarkVersion",
             'commonmark-strikethrough': "com.atlassian.commonmark:commonmark-ext-gfm-strikethrough:$commonMarkVersion",
             'commonmark-table'        : "com.atlassian.commonmark:commonmark-ext-gfm-tables:$commonMarkVersion",

markwon-core/build.gradle

@@ -18,6 +18,10 @@ dependencies {
     deps.with {
         api it['x-annotations']
         api it['commonmark']
+
+        // @since 4.1.0-SNAPSHOT to allow PrecomputedTextSetterCompat
+        // note that this dependency must be added on a client side explicitly
+        compileOnly it['x-core']
     }
 
     deps['test'].with {

markwon-core/src/main/java/io/noties/markwon/Markwon.java

@@ -123,7 +123,7 @@ public abstract class Markwon {
      * Interface to set text on a TextView. Primary goal is to give a way to use PrecomputedText
      * functionality
      *
-     * @see PrecomputedTextSetter
+     * @see PrecomputedTextSetterCompat
      * @since 4.1.0-SNAPSHOT
      */
     public interface TextSetter {

markwon-core/src/main/java/io/noties/markwon/PrecomputedTextSetter.java

@@ -1,80 +0,0 @@
-package io.noties.markwon;
-
-import android.os.AsyncTask;
-import android.os.Build;
-import android.text.PrecomputedText;
-import android.text.Spanned;
-import android.widget.TextView;
-
-import androidx.annotation.NonNull;
-import androidx.annotation.Nullable;
-import androidx.annotation.RequiresApi;
-
-import java.lang.ref.WeakReference;
-import java.util.concurrent.Executor;
-
-/**
- * @see io.noties.markwon.Markwon.TextSetter
- * @since 4.1.0-SNAPSHOT
- */
-@RequiresApi(Build.VERSION_CODES.P)
-public class PrecomputedTextSetter implements Markwon.TextSetter {
-
-    @NonNull
-    public static PrecomputedTextSetter create() {
-        return create(AsyncTask.THREAD_POOL_EXECUTOR);
-    }
-
-    @NonNull
-    public static PrecomputedTextSetter create(@NonNull Executor executor) {
-        return new PrecomputedTextSetter(executor);
-    }
-
-    private final Executor executor;
-
-    @SuppressWarnings("WeakerAccess")
-    PrecomputedTextSetter(@NonNull Executor executor) {
-        this.executor = executor;
-    }
-
-    @Override
-    public void setText(
-            @NonNull TextView textView,
-            @NonNull final Spanned markdown,
-            @NonNull final TextView.BufferType bufferType,
-            @NonNull final Runnable onComplete) {
-        final WeakReference<TextView> reference = new WeakReference<>(textView);
-        executor.execute(new Runnable() {
-            @Override
-            public void run() {
-                final PrecomputedText precomputedText = precomputedText(reference.get(), markdown);
-                if (precomputedText != null) {
-                    apply(reference.get(), precomputedText, bufferType, onComplete);
-                }
-            }
-        });
-    }
-
-    @Nullable
-    private static PrecomputedText precomputedText(@Nullable TextView textView, @NonNull Spanned spanned) {
-        return textView == null
-                ? null
-                : PrecomputedText.create(spanned, textView.getTextMetricsParams());
-    }
-
-    private static void apply(
-            @Nullable final TextView textView,
-            @NonNull final PrecomputedText precomputedText,
-            @NonNull final TextView.BufferType bufferType,
-            @NonNull final Runnable onComplete) {
-        if (textView != null) {
-            textView.post(new Runnable() {
-                @Override
-                public void run() {
-                    textView.setText(precomputedText, bufferType);
-                    onComplete.run();
-                }
-            });
-        }
-    }
-}

markwon-core/src/main/java/io/noties/markwon/PrecomputedTextSetterCompat.java

@@ -0,0 +1,120 @@
+package io.noties.markwon;
+
+import android.os.Build;
+import android.text.Spanned;
+import android.util.Log;
+import android.widget.TextView;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.core.text.PrecomputedTextCompat;
+
+import java.lang.ref.WeakReference;
+import java.util.concurrent.Executor;
+
+/**
+ * Please note this class requires `androidx.core:core` artifact being explicitly added to your dependencies.
+ * Please do not use with `markwon-recycler` as it will lead to bad item rendering (due to async nature)
+ *
+ * @see io.noties.markwon.Markwon.TextSetter
+ * @since 4.1.0-SNAPSHOT
+ */
+public class PrecomputedTextSetterCompat implements Markwon.TextSetter {
+
+    /**
+     * @param executor for background execution of text pre-computation
+     */
+    @NonNull
+    public static PrecomputedTextSetterCompat create(@NonNull Executor executor) {
+        return new PrecomputedTextSetterCompat(executor);
+    }
+
+    private final Executor executor;
+
+    @SuppressWarnings("WeakerAccess")
+    PrecomputedTextSetterCompat(@NonNull Executor executor) {
+        this.executor = executor;
+    }
+
+    @Override
+    public void setText(
+            @NonNull TextView textView,
+            @NonNull final Spanned markdown,
+            @NonNull final TextView.BufferType bufferType,
+            @NonNull final Runnable onComplete) {
+
+        // insert version check and do not execute on a device < 21
+        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP) {
+            // it's still no-op, so there is no need to start background execution
+            applyText(textView, markdown, bufferType, onComplete);
+            return;
+        }
+
+        final WeakReference<TextView> reference = new WeakReference<>(textView);
+        executor.execute(new Runnable() {
+            @Override
+            public void run() {
+                try {
+                    final PrecomputedTextCompat precomputedTextCompat = precomputedText(reference.get(), markdown);
+                    if (precomputedTextCompat != null) {
+                        applyText(reference.get(), precomputedTextCompat, bufferType, onComplete);
+                    }
+                } catch (Throwable t) {
+                    Log.e("PrecomputdTxtSetterCmpt", "Exception during pre-computing text", t);
+                    // apply initial markdown
+                    applyText(reference.get(), markdown, bufferType, onComplete);
+                }
+            }
+        });
+    }
+
+    @Nullable
+    private static PrecomputedTextCompat precomputedText(@Nullable TextView textView, @NonNull Spanned spanned) {
+
+        if (textView == null) {
+            return null;
+        }
+
+        final PrecomputedTextCompat.Params params;
+
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.P) {
+            // use native parameters on P
+            params = new PrecomputedTextCompat.Params(textView.getTextMetricsParams());
+        } else {
+
+            final PrecomputedTextCompat.Params.Builder builder =
+                    new PrecomputedTextCompat.Params.Builder(textView.getPaint());
+
+            // please note that text-direction initialization is omitted
+            // by default it will be determined by the first locale-specific character
+
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
+                // another miss on API surface, this can easily be done by the compat class itself
+                builder
+                        .setBreakStrategy(textView.getBreakStrategy())
+                        .setHyphenationFrequency(textView.getHyphenationFrequency());
+            }
+
+            params = builder.build();
+        }
+
+        return PrecomputedTextCompat.create(spanned, params);
+    }
+
+    private static void applyText(
+            @Nullable final TextView textView,
+            @NonNull final Spanned text,
+            @NonNull final TextView.BufferType bufferType,
+            @NonNull final Runnable onComplete) {
+        Log.e("TXT", String.format("thread: %s, attached: %s", Thread.currentThread(), textView.isAttachedToWindow()));
+        if (textView != null) {
+            textView.post(new Runnable() {
+                @Override
+                public void run() {
+                    textView.setText(text, bufferType);
+                    onComplete.run();
+                }
+            });
+        }
+    }
+}

sample/build.gradle

@@ -49,6 +49,7 @@ dependencies {
 
     deps.with {
         implementation it['x-recycler-view']
+        implementation it['x-core'] // for precomputedTextCompat
         implementation it['okhttp']
         implementation it['prism4j']
         implementation it['debug']

sample/src/main/AndroidManifest.xml

@@ -27,6 +27,7 @@
         <activity android:name=".html.HtmlActivity" />
         <activity android:name=".simpleext.SimpleExtActivity" />
         <activity android:name=".customextension2.CustomExtensionActivity2" />
+        <activity android:name=".precomputed.PrecomputedActivity" />
 
     </application>
 

sample/src/main/java/io/noties/markwon/sample/MainActivity.java

@@ -24,6 +24,7 @@ import io.noties.markwon.sample.customextension.CustomExtensionActivity;
 import io.noties.markwon.sample.customextension2.CustomExtensionActivity2;
 import io.noties.markwon.sample.html.HtmlActivity;
 import io.noties.markwon.sample.latex.LatexActivity;
+import io.noties.markwon.sample.precomputed.PrecomputedActivity;
 import io.noties.markwon.sample.recycler.RecyclerActivity;
 import io.noties.markwon.sample.simpleext.SimpleExtActivity;
 
@@ -112,6 +113,10 @@ public class MainActivity extends Activity {
                 activity = CustomExtensionActivity2.class;
                 break;
 
+            case PRECOMPUTED_TEXT:
+                activity = PrecomputedActivity.class;
+                break;
+
             default:
                 throw new IllegalStateException("No Activity is associated with sample-item: " + item);
         }

sample/src/main/java/io/noties/markwon/sample/Sample.java

@@ -19,7 +19,9 @@ public enum Sample {
 
     SIMPLE_EXT(R.string.sample_simple_ext),
 
-    CUSTOM_EXTENSION_2(R.string.sample_custom_extension_2);
+    CUSTOM_EXTENSION_2(R.string.sample_custom_extension_2),
+
+    PRECOMPUTED_TEXT(R.string.sample_precomputed_text);
 
     private final int textResId;
 

sample/src/main/java/io/noties/markwon/sample/precomputed/PrecomputedActivity.java

@@ -0,0 +1,38 @@
+package io.noties.markwon.sample.precomputed;
+
+import android.app.Activity;
+import android.os.Bundle;
+import android.widget.TextView;
+
+import androidx.annotation.Nullable;
+
+import java.util.concurrent.Executors;
+
+import io.noties.markwon.Markwon;
+import io.noties.markwon.PrecomputedTextSetterCompat;
+import io.noties.markwon.sample.R;
+
+public class PrecomputedActivity extends Activity {
+
+    @Override
+    public void onCreate(@Nullable Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_text_view);
+
+        final Markwon markwon = Markwon.builder(this)
+                // please note that precomputedTextCompat is no-op on devices lower than L (21)
+                .textSetter(PrecomputedTextSetterCompat.create(Executors.newCachedThreadPool()))
+                .build();
+
+        final TextView textView = findViewById(R.id.text_view);
+        final String markdown = "# Hello!\n\n" +
+                "This _displays_ how to implement and use `PrecomputedTextCompat` with the **Markwon**\n\n" +
+                "> consider using PrecomputedText only if your markdown content is large enough\n> \n" +
+                "> **please note** that it works badly with `markwon-recycler` due to asynchronous nature";
+
+        // please note that _sometimes_ (if done without `post` here) further `textView.post`
+        // (that is used in PrecomputedTextSetterCompat to deliver result to main-thread) won't be called
+        // making the result of pre-computation absent and text-view clear (no text)
+        textView.post(() -> markwon.setMarkdown(textView, markdown));
+    }
+}

sample/src/main/res/values/strings-samples.xml

@@ -23,4 +23,6 @@
     <string name="sample_custom_extension_2"># \# Custom extension 2\n\nAutomatically
         convert `#1` and `@user` to Github links</string>
 
+    <string name="sample_precomputed_text"># \# PrecomputedText\n\nUsage of TextSetter and PrecomputedTextCompat</string>
+
 </resources>