Drawing thumbnail background color for empty space in view.

- When showing landscape thumbnails in portrait, the thumbnails are
  aspect scaled to fit the width of the view, this change will draw
  a solid color to fill the other part so that we don't see the
  current edge-clamp texture effect.

Change-Id: Icf08239942f9179c66ba0f8d8ddd00f7d2a09d3c

packages/SystemUI/src/com/android/systemui/recents/views/TaskViewThumbnail.java

@@ -25,6 +25,7 @@ import android.graphics.LightingColorFilter;
 import android.graphics.Matrix;
 import android.graphics.Paint;
 import android.graphics.Rect;
+import android.graphics.Region;
 import android.graphics.Shader;
 import android.util.AttributeSet;
 import android.view.View;
@@ -48,6 +49,7 @@ public class TaskViewThumbnail extends View {
     float mDimAlpha;
     Matrix mScaleMatrix = new Matrix();
     Paint mDrawPaint = new Paint();
+    Paint mBgFillPaint = new Paint();
     BitmapShader mBitmapShader;
     LightingColorFilter mLightingColorFilter = new LightingColorFilter(0xffffffff, 0);
 
@@ -79,6 +81,7 @@ public class TaskViewThumbnail extends View {
         mDrawPaint.setAntiAlias(true);
         mCornerRadius = getResources().getDimensionPixelSize(
                 R.dimen.recents_task_view_rounded_corners_radius);
+        mBgFillPaint.setColor(Color.WHITE);
     }
 
     /**
@@ -100,10 +103,37 @@ public class TaskViewThumbnail extends View {
         if (mInvisible) {
             return;
         }
-        // Draw the thumbnail with the rounded corners
-        canvas.drawRoundRect(0, 0, mTaskViewRect.width(), mTaskViewRect.height(),
-                mCornerRadius,
-                mCornerRadius, mDrawPaint);
+
+        if (mThumbnailRect.width() <= 0 || mThumbnailRect.height() <= 0 ||
+                mTaskViewRect.width() <= 0 || mTaskViewRect.height() <= 0) {
+            return;
+        }
+
+        int thumbnailHeight = (int) (((float) mTaskViewRect.width() / mThumbnailRect.width()) *
+                mThumbnailRect.height());
+        if (thumbnailHeight >= mTaskViewRect.height()) {
+            // The thumbnail fills the full task view bounds, so just draw it
+            canvas.drawRoundRect(0, 0, mTaskViewRect.width(), mTaskViewRect.height(),
+                    mCornerRadius, mCornerRadius, mDrawPaint);
+        } else {
+            // The thumbnail only covers part of the task view bounds, so fill in the non-thumbnail
+            // space with the default background color.  This is the equivalent of the GL border
+            // texture mode.
+            int count = canvas.save(Canvas.CLIP_SAVE_FLAG);
+
+            // Since we want the top corners to be rounded, just clip at the thumbnail height
+            canvas.clipRect(0, 0, mTaskViewRect.width(), thumbnailHeight, Region.Op.REPLACE);
+            canvas.drawRoundRect(0, 0, mTaskViewRect.width(), thumbnailHeight + mCornerRadius,
+                    mCornerRadius, mCornerRadius, mDrawPaint);
+
+            // In the remaining space, draw the background color
+            canvas.clipRect(0, thumbnailHeight, mTaskViewRect.width(), mTaskViewRect.height(),
+                    Region.Op.REPLACE);
+            canvas.drawRoundRect(0, thumbnailHeight - mCornerRadius, mTaskViewRect.width(),
+                    mTaskViewRect.height(), mCornerRadius, mCornerRadius, mBgFillPaint);
+
+            canvas.restoreToCount(count);
+        }
     }
 
     /** Sets the thumbnail to a given bitmap. */