Limiting the magnified region

1. Get the real display size including the status and navigation bar.
2. Calculate the real position of magnification frame
(i.e. mirror window) based on the magnified region should be limited
by the region of the display.

Bug: 143451908
Test: manual test
Change-Id: I907b005f960bc2e254b73691d7ac8d80cdf92a16

packages/SystemUI/src/com/android/systemui/accessibility/WindowMagnificationController.java

@@ -86,6 +86,8 @@ public class WindowMagnificationController implements View.OnClickListener,
     private SurfaceView mMirrorSurfaceView;
     private View mControlsView;
     private View mOverlayView;
+    // The boundary of magnification frame.
+    private final Rect mMagnificationFrameBoundary = new Rect();
 
     private MoveMirrorRunnable mMoveMirrorRunnable = new MoveMirrorRunnable();
 
@@ -93,7 +95,7 @@ public class WindowMagnificationController implements View.OnClickListener,
         mContext = context;
         mHandler = handler;
         Display display = mContext.getDisplay();
-        display.getSize(mDisplaySize);
+        display.getRealSize(mDisplaySize);
         mDisplayId = mContext.getDisplayId();
 
         mWm = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
@@ -114,6 +116,7 @@ public class WindowMagnificationController implements View.OnClickListener,
             return;
         }
         setInitialStartBounds();
+        setMagnificationFrameBoundary();
         createOverlayWindow();
     }
 
@@ -330,7 +333,7 @@ public class WindowMagnificationController implements View.OnClickListener,
     @Override
     public void onClick(View v) {
         setMoveOffset(v, mMoveFrameAmountShort);
-        moveMirrorFromControls();
+        moveMirrorWindow(mMoveWindowOffset.x, mMoveWindowOffset.y);
     }
 
     @Override
@@ -370,10 +373,8 @@ public class WindowMagnificationController implements View.OnClickListener,
             case MotionEvent.ACTION_MOVE:
                 int xDiff = (int) (event.getRawX() - mLastDrag.x);
                 int yDiff = (int) (event.getRawY() - mLastDrag.y);
-                mMagnificationFrame.offset(xDiff, yDiff);
+                moveMirrorWindow(xDiff, yDiff);
                 mLastDrag.set(event.getRawX(), event.getRawY());
-                modifyWindowMagnification(mTransaction);
-                mTransaction.apply();
                 return true;
         }
         return false;
@@ -393,11 +394,11 @@ public class WindowMagnificationController implements View.OnClickListener,
         }
     }
 
-    private void moveMirrorFromControls() {
-        mMagnificationFrame.offset(mMoveWindowOffset.x, mMoveWindowOffset.y);
-
-        modifyWindowMagnification(mTransaction);
-        mTransaction.apply();
+    private void moveMirrorWindow(int xOffset, int yOffset) {
+        if (updateMagnificationFramePosition(xOffset, yOffset)) {
+            modifyWindowMagnification(mTransaction);
+            mTransaction.apply();
+        }
     }
 
     /**
@@ -414,6 +415,52 @@ public class WindowMagnificationController implements View.OnClickListener,
         return new Rect(left, top, right, bottom);
     }
 
+    private void setMagnificationFrameBoundary() {
+        // Calculates width and height for magnification frame could exceed out the screen.
+        // TODO : re-calculating again when scale is changed.
+        // The half width of magnification frame.
+        final int halfWidth = mMagnificationFrame.width() / 2;
+        // The half height of magnification frame.
+        final int halfHeight = mMagnificationFrame.height() / 2;
+        // The scaled half width of magnified region.
+        final int scaledWidth = (int) (halfWidth / mScale);
+        // The scaled half height of magnified region.
+        final int scaledHeight = (int) (halfHeight / mScale);
+        final int exceededWidth = halfWidth - scaledWidth;
+        final int exceededHeight = halfHeight - scaledHeight;
+
+        mMagnificationFrameBoundary.set(-exceededWidth, -exceededHeight,
+                mDisplaySize.x + exceededWidth, mDisplaySize.y + exceededHeight);
+    }
+
+    /**
+     * Calculates and sets the real position of magnification frame based on the magnified region
+     * should be limited by the region of the display.
+     */
+    private boolean updateMagnificationFramePosition(int xOffset, int yOffset) {
+        mTmpRect.set(mMagnificationFrame);
+        mTmpRect.offset(xOffset, yOffset);
+
+        if (mTmpRect.left < mMagnificationFrameBoundary.left) {
+            mTmpRect.offsetTo(mMagnificationFrameBoundary.left, mTmpRect.top);
+        } else if (mTmpRect.right > mMagnificationFrameBoundary.right) {
+            final int leftOffset = mMagnificationFrameBoundary.right - mMagnificationFrame.width();
+            mTmpRect.offsetTo(leftOffset, mTmpRect.top);
+        }
+
+        if (mTmpRect.top < mMagnificationFrameBoundary.top) {
+            mTmpRect.offsetTo(mTmpRect.left, mMagnificationFrameBoundary.top);
+        } else if (mTmpRect.bottom > mMagnificationFrameBoundary.bottom) {
+            final int topOffset = mMagnificationFrameBoundary.bottom - mMagnificationFrame.height();
+            mTmpRect.offsetTo(mTmpRect.left, topOffset);
+        }
+
+        if (!mTmpRect.equals(mMagnificationFrame)) {
+            mMagnificationFrame.set(mTmpRect);
+            return true;
+        }
+        return false;
+    }
     @Override
     public void surfaceCreated(SurfaceHolder holder) {
         createMirror();
@@ -431,7 +478,7 @@ public class WindowMagnificationController implements View.OnClickListener,
         @Override
         public void run() {
             if (mIsPressedDown) {
-                moveMirrorFromControls();
+                moveMirrorWindow(mMoveWindowOffset.x, mMoveWindowOffset.y);
                 mHandler.postDelayed(mMoveMirrorRunnable, 100);
             }
         }