Scrollbar support (#30)

* added xml attributes for both horizontal and vertical scrollbars
added implementations for scrollXXX methods (wip)

* scrollbars do work for symmetric but don't work yet for asymmetric content

* fixed scrollbars for asymmetric content

* added scrollbar xml tag to imageview
removed unnecessary tags

* moved companion methods closer together
removed todo

* fixed scrollbars getting rendered behind content

* review fixes

* review fix

* merge fix

app/src/main/res/layout/activity_main.xml

@@ -11,6 +11,7 @@
  android:layout_width="match_parent"
  android:layout_height="0dp"
  android:layout_weight="1"
+ android:scrollbars="horizontal|vertical"
  app:hasClickableChildren="true"
  app:horizontalPanEnabled="true"
  app:verticalPanEnabled="true"
@@ -27,7 +28,11 @@
  android:layout_width="match_parent"
  android:layout_height="0dp"
  android:layout_weight="1"
- android:visibility="gone" />
+ android:scrollbars="horizontal|vertical"
+ android:visibility="gone"
+ app:horizontalPanEnabled="true"
+ app:verticalPanEnabled="true"
+ app:zoomEnabled="true" />
 
  <LinearLayout
  android:layout_width="match_parent"

library/src/main/java/com/otaliastudios/zoom/ZoomImageView.java

@@ -95,12 +95,34 @@ public boolean onTouchEvent(MotionEvent ev) {
  public void onUpdate(ZoomEngine helper, Matrix matrix) {
  mMatrix.set(matrix);
  setImageMatrix(mMatrix);
+
+ awakenScrollBars();
  }
 
  @Override
  public void onIdle(ZoomEngine engine) {
  }
 
+ @Override
+ protected int computeHorizontalScrollOffset() {
+ return (int) (-1 * mEngine.getPanX() * mEngine.getRealZoom());
+ }
+
+ @Override
+ protected int computeHorizontalScrollRange() {
+ return (int) (mDrawableRect.width() * mEngine.getRealZoom());
+ }
+
+ @Override
+ protected int computeVerticalScrollOffset() {
+ return (int) (-1 * mEngine.getPanY() * mEngine.getRealZoom());
+ }
+
+ @Override
+ protected int computeVerticalScrollRange() {
+ return (int) (mDrawableRect.height() * mEngine.getRealZoom());
+ }
+
  //endregion
 
  //region APIs

library/src/main/java/com/otaliastudios/zoom/ZoomLayout.java

@@ -80,6 +80,8 @@ public ZoomLayout(@NonNull Context context, @Nullable AttributeSet attrs, @AttrR
  if (minZoom > -1) setMinZoom(minZoom, minZoomMode);
  if (maxZoom > -1) setMaxZoom(maxZoom, maxZoomMode);
  setHasClickableChildren(hasChildren);
+
+ setWillNotDraw(false);
  }
 
  //region Internal
@@ -156,23 +158,48 @@ public void onUpdate(ZoomEngine helper, Matrix matrix) {
  } else {
  invalidate();
  }
+
+ awakenScrollBars();
  }
 
  @Override
  public void onIdle(ZoomEngine engine) {
  }
 
+ @Override
+ protected int computeHorizontalScrollOffset() {
+ return (int) (-1 * mEngine.getPanX() * mEngine.getRealZoom());
+ }
+
+ @Override
+ protected int computeHorizontalScrollRange() {
+ return (int) (mChildRect.width() * mEngine.getRealZoom());
+ }
+
+ @Override
+ protected int computeVerticalScrollOffset() {
+ return (int) (-1 * mEngine.getPanY() * mEngine.getRealZoom());
+ }
+
+ @Override
+ protected int computeVerticalScrollRange() {
+ return (int) (mChildRect.height() * mEngine.getRealZoom());
+ }
+
  @Override
  protected boolean drawChild(Canvas canvas, View child, long drawingTime) {
+ boolean result;
+
  if (!mHasClickableChildren) {
  int save = canvas.save();
  canvas.setMatrix(mMatrix);
- boolean result = super.drawChild(canvas, child, drawingTime);
+ result = super.drawChild(canvas, child, drawingTime);
  canvas.restoreToCount(save);
- return result;
  } else {
- return super.drawChild(canvas, child, drawingTime);
+ result = super.drawChild(canvas, child, drawingTime);
  }
+
+ return result;
  }
 
  //endregion