From 879dde138298718c6d9f61c10189b30aa19fd4e8 Mon Sep 17 00:00:00 2001
From: Dimitry Ivanov <di@noties.io>
Date: Thu, 4 Jul 2019 17:26:03 +0300
Subject: [PATCH] Scale down LaTeX formula if exceed canvas width (keep ratio)

---
 .../markwon/ext/latex/JLatexMathPlugin.java   | 23 +++++++---
 .../markwon/sample/latex/LatexActivity.java   | 44 +++++++++----------
 2 files changed, 40 insertions(+), 27 deletions(-)

diff --git a/markwon-ext-latex/src/main/java/io/noties/markwon/ext/latex/JLatexMathPlugin.java b/markwon-ext-latex/src/main/java/io/noties/markwon/ext/latex/JLatexMathPlugin.java
index 291d361a..5d136ece 100644
--- a/markwon-ext-latex/src/main/java/io/noties/markwon/ext/latex/JLatexMathPlugin.java
+++ b/markwon-ext-latex/src/main/java/io/noties/markwon/ext/latex/JLatexMathPlugin.java
@@ -361,12 +361,25 @@ public class JLatexMathPlugin extends AbstractMarkwonPlugin {
             final Rect imageBounds = drawable.getResult().getBounds();
             final int canvasWidth = drawable.getLastKnownCanvasWidth();
 
-            // todo: scale down when formula is greater than width (keep ratio and apply height)
+            if (fitCanvas) {
 
-            if (fitCanvas
-                    && imageBounds.width() < canvasWidth) {
-                // we increase only width (keep height as-is)
-                return new Rect(0, 0, canvasWidth, imageBounds.height());
+                // we modify bounds only if `fitCanvas` is true
+                final int w = imageBounds.width();
+
+                if (w < canvasWidth) {
+                    // increase width and center formula (keep height as-is)
+                    return new Rect(0, 0, canvasWidth, imageBounds.height());
+                }
+
+                // @since 4.0.2 we additionally scale down the resulting formula (keeping the ratio)
+                // the thing is - JLatexMathDrawable will do it anyway, but it will modify its own
+                // bounds (which AsyncDrawable won't catch), thus leading to an empty space after the formula
+                if (w > canvasWidth) {
+                    // here we must scale it down (keeping the ratio)
+                    final float ratio = (float) w / imageBounds.height();
+                    final int h = (int) (canvasWidth / ratio + .5F);
+                    return new Rect(0, 0, canvasWidth, h);
+                }
             }
 
             return imageBounds;
diff --git a/sample/src/main/java/io/noties/markwon/sample/latex/LatexActivity.java b/sample/src/main/java/io/noties/markwon/sample/latex/LatexActivity.java
index 7adee8e8..44d9aac3 100644
--- a/sample/src/main/java/io/noties/markwon/sample/latex/LatexActivity.java
+++ b/sample/src/main/java/io/noties/markwon/sample/latex/LatexActivity.java
@@ -66,29 +66,29 @@ public class LatexActivity extends Activity {
 //                }))
                 .usePlugin(JLatexMathPlugin.create(textView.getTextSize()))
                 .build();
-
-        if (true) {
-//            final String l = "$$\n" +
-//                    "  P(X=r)=\\frac{\\lambda^r e^{-\\lambda}}{r!}\n" +
-//                    "$$\n" +
-//                    "\n" +
-//                    "$$\n" +
-//                    "  P(X<r)=P(X<r-1)\n" +
-//                    "$$\n" +
-//                    "\n" +
-//                    "$$\n" +
-//                    "  P(X>r)=1-P(X<r=1)\n" +
-//                    "$$\n" +
-//                    "\n" +
-//                    "$$\n" +
-//                    "  \\text{Variance} = \\lambda\n" +
+//
+//        if (true) {
+////            final String l = "$$\n" +
+////                    "  P(X=r)=\\frac{\\lambda^r e^{-\\lambda}}{r!}\n" +
+////                    "$$\n" +
+////                    "\n" +
+////                    "$$\n" +
+////                    "  P(X<r)=P(X<r-1)\n" +
+////                    "$$\n" +
+////                    "\n" +
+////                    "$$\n" +
+////                    "  P(X>r)=1-P(X<r=1)\n" +
+////                    "$$\n" +
+////                    "\n" +
+////                    "$$\n" +
+////                    "  \\text{Variance} = \\lambda\n" +
+////                    "$$";
+//            final String l = "$$ \n" +
+//                    "    \\sigma_T^2 = \\frac{1-p}{p^2}\n" +
 //                    "$$";
-            final String l = "$$ \n" +
-                    "    \\sigma_T^2 = \\frac{1-p}{p^2}\n" +
-                    "$$";
-            markwon.setMarkdown(textView, l);
-            return;
-        }
+//            markwon.setMarkdown(textView, l);
+//            return;
+//        }
 
         markwon.setMarkdown(textView, markdown);
     }