private void limitPan() {
final float aspectQuotient = mAspectQuotient.get();
final float zoomX = mState.getZoomX(aspectQuotient);
final float zoomY = mState.getZoomY(aspectQuotient);
final float panMinX = .5f - getMaxPanDelta(zoomX);
final float panMaxX = .5f + getMaxPanDelta(zoomX);
final float panMinY = .5f - getMaxPanDelta(zoomY);
final float panMaxY = .5f + getMaxPanDelta(zoomY);
if (mState.getPanX() > panMaxX) {
mState.setPanX(panMaxX);
}
if (mState.getPanX() < panMinX) {
mState.setPanX(panMinX);
}
if (mState.getPanY() > panMaxY) {
mState.setPanY(panMaxY);
}
if (mState.getPanY() < panMinY) {
mState.setPanY(panMinY);
}
}
private void limitZoom() {
if (mState.getZoom() > MAX_ZOOM) {
mState.setZoom(MAX_ZOOM);
}
if (mState.getZoom() < MIN_ZOOM) {
mState.setZoom(MIN_ZOOM);
}
}
/**
* Set object holding the zoom state that should be used
*
* @param state The zoom state
*/
public void setZoomState(ZoomState state) {
if (mState != null) {
mState.deleteObserver(this);
}
mState = state;
mState.addObserver(this);
invalidate();
}
@Override
protected void onDraw(Canvas canvas) {
if (mBitmap != null && mState != null) {
final int viewWidth = getWidth();
final int viewHeight = getHeight();
final int bitmapWidth = mBitmap.getWidth();
final int bitmapHeight = mBitmap.getHeight();
final float panX = mState.getPanX();
final float panY = mState.getPanY();
final float zoomX = mState.getZoomX(mAspectQuotient) * viewWidth / bitmapWidth;
final float zoomY = mState.getZoomY(mAspectQuotient) * viewHeight / bitmapHeight;
// Setup source and destination rectangles
mRectSrc.left = (int) (panX * bitmapWidth - viewWidth / (zoomX * 2));
mRectSrc.top = (int) (panY * bitmapHeight - viewHeight / (zoomY * 2));
mRectSrc.right = (int) (mRectSrc.left + viewWidth / zoomX);
mRectSrc.bottom = (int) (mRectSrc.top + viewHeight / zoomY);
mRectDst.left = getLeft();
mRectDst.top = getTop();
mRectDst.right = getRight();
mRectDst.bottom = getBottom();
// Adjust source rectangle so that it fits within the source image.
if (mRectSrc.left < 0) {
mRectDst.left += -mRectSrc.left * zoomX;
mRectSrc.left = 0;
}
if (mRectSrc.right > bitmapWidth) {
mRectDst.right -= (mRectSrc.right - bitmapWidth) * zoomX;
mRectSrc.right = bitmapWidth;
}
if (mRectSrc.top < 0) {
mRectDst.top += -mRectSrc.top * zoomY;
mRectSrc.top = 0;
}
if (mRectSrc.bottom > bitmapHeight) {
mRectDst.bottom -= (mRectSrc.bottom - bitmapHeight) * zoomY;
mRectSrc.bottom = bitmapHeight;
}
canvas.drawBitmap(mBitmap, mRectSrc, mRectDst, mPaint);
}
}
public void pan(float dx, float dy) {
final float aspectQuotient = mAspectQuotient.get();
mState.setPanX(mState.getPanX() + dx / mState.getZoomX(aspectQuotient));
mState.setPanY(mState.getPanY() + dy / mState.getZoomY(aspectQuotient));
limitPan();
mState.notifyObservers();
}
public void zoom(float f, float x, float y) {
final float aspectQuotient = mAspectQuotient.get();
final float prevZoomX = mState.getZoomX(aspectQuotient);
final float prevZoomY = mState.getZoomY(aspectQuotient);
mState.setZoom(mState.getZoom() * f);
limitZoom();
final float newZoomX = mState.getZoomX(aspectQuotient);
final float newZoomY = mState.getZoomY(aspectQuotient);
mState.setPanX(mState.getPanX() + (x - .5f) * (1f / prevZoomX - 1f / newZoomX));
mState.setPanY(mState.getPanY() + (y - .5f) * (1f / prevZoomY - 1f / newZoomY));
limitPan();
mState.notifyObservers();
}
public boolean isZoomed() {
return mState.isZoomed();
}
private void resetZoomState() {
mZoomState.setPanX(0.5f);
mZoomState.setPanY(0.5f);
mZoomState.setZoom(1f);
mZoomState.notifyObservers();
}