Fixing a cursor position initialization problem

remoting/android/java/src/org/chromium/chromoting/TouchInputHandler.java

Index: remoting/android/java/src/org/chromium/chromoting/TouchInputHandler.java
diff --git a/remoting/android/java/src/org/chromium/chromoting/TouchInputHandler.java b/remoting/android/java/src/org/chromium/chromoting/TouchInputHandler.java
index 4cbd35ed60803a8945067e13135d52748f44e497..14674fe5269f20fe881c4b3a68a732eb22e5199e 100644
--- a/remoting/android/java/src/org/chromium/chromoting/TouchInputHandler.java
+++ b/remoting/android/java/src/org/chromium/chromoting/TouchInputHandler.java
@@ -361,8 +361,12 @@ public class TouchInputHandler {
         synchronized (mRenderData) {
             screenCenterX = (float) mRenderData.screenWidth / 2;
             screenCenterY = (float) mRenderData.screenHeight / 2;
+
+            float[] imagePoint = mapScreenPointToImagePoint(screenCenterX, screenCenterY);
+            mDesktopCanvas.setViewportPosition(imagePoint[0], imagePoint[1]);
         }
         moveCursorToScreenPoint(screenCenterX, screenCenterY);
+        mDesktopCanvas.repositionImage(true);
     }
 
     private void setInputStrategy(InputStrategyInterface inputStrategy) {
@@ -399,13 +403,8 @@ public class TouchInputHandler {
 
     /** Moves the cursor to the specified position on the screen. */
     private void moveCursorToScreenPoint(float screenX, float screenY) {
-        float[] mappedValues = {screenX, screenY};
-        synchronized (mRenderData) {
-            Matrix canvasToImage = new Matrix();
-            mRenderData.transform.invert(canvasToImage);
-            canvasToImage.mapPoints(mappedValues);
-        }
-        moveCursor((int) mappedValues[0], (int) mappedValues[1]);
+        float[] imagePoint = mapScreenPointToImagePoint(screenX, screenY);
+        moveCursor((int) imagePoint[0], (int) imagePoint[1]);
     }
 
     /** Moves the cursor to the specified position on the remote host. */
@@ -437,6 +436,18 @@ public class TouchInputHandler {
         return true;
     }
 
+    /** Translates a point in screen coordinates to a location on the desktop image. */
+    private float[] mapScreenPointToImagePoint(float screenX, float screenY) {
+        float[] mappedPoints = {screenX, screenY};
+        Matrix screenToImage = new Matrix();
+        synchronized (mRenderData) {
+            mRenderData.transform.invert(screenToImage);
+        }
+        screenToImage.mapPoints(mappedPoints);
+
+        return mappedPoints;
+    }
+
     /** Responds to touch events filtered by the gesture detectors. */
     private class GestureListener extends GestureDetector.SimpleOnGestureListener
             implements ScaleGestureDetector.OnScaleGestureListener,
@@ -570,7 +581,7 @@ public class TouchInputHandler {
             }
 
             if (!mInputStrategy.isIndirectInputMode()) {
-                if (!mapScreenPointToImage(x, y)) {
+                if (screenPointLiesOutsideImageBoundary(x, y)) {
                     return false;
                 }
                 moveCursorToScreenPoint(x, y);
@@ -595,7 +606,7 @@ public class TouchInputHandler {
             }
 
             if (!mInputStrategy.isIndirectInputMode()) {
-                if (!mapScreenPointToImage(x, y)) {
+                if (screenPointLiesOutsideImageBoundary(x, y)) {
                     return;
                 }
                 moveCursorToScreenPoint(x, y);
@@ -626,21 +637,18 @@ public class TouchInputHandler {
             }
         }
 
-        /** Verifies the given point maps to a valid location within the desktop image. */
-        private boolean mapScreenPointToImage(float screenX, float screenY) {
-            float[] mappedPoints = {screenX, screenY};
+        /** Determines whether the given screen point lies outside the desktop image. */
+        private boolean screenPointLiesOutsideImageBoundary(float screenX, float screenY) {
+            float[] mappedPoints = mapScreenPointToImagePoint(screenX, screenY);
             int imageWidth;
             int imageHeight;
-            Matrix screenToImage = new Matrix();
             synchronized (mRenderData) {
-                mRenderData.transform.invert(screenToImage);
                 imageWidth = mRenderData.imageWidth;
                 imageHeight = mRenderData.imageHeight;
             }
-            screenToImage.mapPoints(mappedPoints);
 
-            return (mappedPoints[0] >= 0 && mappedPoints[0] <= imageWidth)
-                    && (mappedPoints[1] >= 0 && mappedPoints[1] <= imageHeight);
+            return (mappedPoints[0] < 0 && mappedPoints[0] > imageWidth)

[Lambros, 2016/07/14 21:11:08]

The '&&'s should be ||, and the parentheses are not needed.
Should be: x < 0 || x > width || y < 0 || y > height

Also, because of floating-point rounding errors, perhaps we should allow a
slight margin of error?
x < -epsilon || x > width + epsilon ...
where epsilon is some small number.
Guess it depends what this will be used for?

[joedow, 2016/07/14 21:47:36]

Oh geez, not sure why I didn't catch this in my testing.  Fixed now :)

I'm fine adding a small fudge factor to this as well.

+                    || (mappedPoints[1] < 0 && mappedPoints[1] > imageHeight);
         }
     }
 }