我目前正在开发一个应用程序，我需要一个可以放大的图像视图。我找到了正确的代码，但缩放或拖出时的图像不会停留在图像边框。我将不胜感激，谢谢。
public class test extends Activity implements OnTouchListener {
private static final String TAG = "Touch";
@SuppressWarnings("unused")
private static final float MIN_ZOOM = 1f, MAX_ZOOM = 1f;
// These matrices will be used to scale points of the image
Matrix matrix = new Matrix();
Matrix savedMatrix = new Matrix();
// The 3 states (events) which the user is trying to perform
static final int NONE = 0;
static final int DRAG = 1;
static final int ZOOM = 2;
int mode = NONE;
// these PointF objects are used to record the point(s) the user is touching
PointF start = new PointF();
PointF mid = new PointF();
int picx;
int picy;
float oldDist = 1f;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
ImageView view = (ImageView) findViewById(R.id.imageView1);
view.setOnTouchListener(this);
}
public boolean onTouch(View v, MotionEvent event) {
ImageView view = (ImageView) v;
view.setScaleType(ImageView.ScaleType.MATRIX);
float scale;
dumpEvent(event);
// Handle touch events here...
switch (event.getAction() & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN: // first finger down only
savedMatrix.set(matrix);
start.set(event.getX(), event.getY());
Log.d(TAG, "mode=DRAG"); // write to LogCat
mode = DRAG;
break;
case MotionEvent.ACTION_UP: // first finger lifted
case MotionEvent.ACTION_POINTER_UP: // second finger lifted
mode = NONE;
Log.d(TAG, "mode=NONE");
break;
case MotionEvent.ACTION_POINTER_DOWN: // first and second finger down
oldDist = spacing(event);
Log.d(TAG, "oldDist=" + oldDist);
if (oldDist > 5f) {
savedMatrix.set(matrix);
midPoint(mid, event);
mode = ZOOM;
Log.d(TAG, "mode=ZOOM");
}
break;
case MotionEvent.ACTION_MOVE:
if (mode == DRAG) {
matrix.set(savedMatrix);
matrix.postTranslate(event.getX() - start.x, event.getY()
- start.y); // create the transformation in the matrix
// of points
} else if (mode == ZOOM) {
// pinch zooming
float newDist = spacing(event);
Log.d(TAG, "newDist=" + newDist);
if (newDist > 5f) {
matrix.set(savedMatrix);
scale = newDist / oldDist; // setting the scaling of the
// matrix...if scale > 1 means
// zoom in...if scale < 1 means
// zoom out
matrix.postScale(scale, scale, mid.x, mid.y);
}
}
break;
}
view.setImageMatrix(matrix); // display the transformation on screen
return true; // indicate event was handled
}
/*
* --------------------------------------------------------------------------
* Method: spacing Parameters: MotionEvent Returns: float Description:
* checks the spacing between the two fingers on touch
* ----------------------------------------------------
*/
private float spacing(MotionEvent event) {
float x = event.getX(0) - event.getX(1);
float y = event.getY(0) - event.getY(1);
return FloatMath.sqrt(x * x + y * y);
}
/*
* --------------------------------------------------------------------------
* Method: midPoint Parameters: PointF object, MotionEvent Returns: void
* Description: calculates the midpoint between the two fingers
* ------------------------------------------------------------
*/
private void midPoint(PointF point, MotionEvent event) {
float x = event.getX(0) + event.getX(1);
float y = event.getY(0) + event.getY(1);
point.set(x / 2, y / 2);
}
/** Show an event in the LogCat view, for debugging */
private void dumpEvent(MotionEvent event) {
String names[] = { "DOWN", "UP", "MOVE", "CANCEL", "OUTSIDE",
"POINTER_DOWN", "POINTER_UP", "7?", "8?", "9?" };
StringBuilder sb = new StringBuilder();
int action = event.getAction();
int actionCode = action & MotionEvent.ACTION_MASK;
sb.append("event ACTION_").append(names[actionCode]);
if (actionCode == MotionEvent.ACTION_POINTER_DOWN
|| actionCode == MotionEvent.ACTION_POINTER_UP) {
sb.append("(pid ").append(
action >> MotionEvent.ACTION_POINTER_ID_SHIFT);
sb.append(")");
}
sb.append("[");
for (int i = 0; i < event.getPointerCount(); i++) {
sb.append("#").append(i);
sb.append("(pid ").append(event.getPointerId(i));
sb.append(")=").append((int) event.getX(i));
sb.append(",").append((int) event.getY(i));
if (i + 1 < event.getPointerCount())
sb.append(";");
}
sb.append("]");
Log.d("Touch Events ---------", sb.toString());
}
}
答案 0 :(得分：0)
很难对矩阵这么做，所以我用一些数学解决方案编写了一些代码来实现这一点。
使用此视图的zoomIn（），zoomOut，setBitmapResource（）。
public class ZoomView extends View {
public static interface ZoomViewClickListner{
void onZoomViewClick(View v);
}
public ZoomView(Context context) {
super(context);
}
private ZoomViewClickListner zoomViewClickListener;
private int viewHeight;
private int viewWidth;
private float ratio;
private float zoomFactor = 2f;
private Bitmap image;
private Rect drawingRect;
private int offsetX = 0, offsetY = 0;
private int drawingHeight;
private int drawingWidth;
private boolean scrollableHorizontal = false;
private boolean scrollableVertical = false;
public ZoomView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public void setZoomViewClickListener(ZoomViewClickListner zoomViewClickListener) {
this.zoomViewClickListener = zoomViewClickListener;
}
@Override
protected void onDraw(Canvas canvas) {
viewHeight = getHeight();
viewWidth = getWidth();
drawingHeight = (int) (viewHeight * zoomFactor);
drawingWidth = (int) (ratio * viewHeight * zoomFactor);
// System.out.println("height:::"+viewHeight+" width:::"+viewWidth);
drawingRect = new Rect((viewWidth-drawingWidth)/2 + offsetX, (viewHeight - drawingHeight)/2 + offsetY, (drawingWidth+(viewWidth-drawingWidth)/2) + offsetX,(viewHeight - drawingHeight)/2+drawingHeight + offsetY);
if(image != null)
canvas.drawBitmap(image, null, drawingRect, null);
if(viewHeight < drawingHeight) scrollableVertical = true;
else scrollableVertical = false;
if(viewWidth < drawingWidth) scrollableHorizontal = true;
else scrollableHorizontal = false;
super.onDraw(canvas);
}
float touchX, touchY , initOffsetX, initOffsetY ;
@Override
public boolean onTouchEvent(MotionEvent event) {
switch(event.getAction()){
case MotionEvent.ACTION_DOWN:
touchX = event.getX();
touchY = event.getY();
initOffsetX = offsetX;
initOffsetY = offsetY;
break;
case MotionEvent.ACTION_MOVE:
if(scrollableVertical){
offsetY = (int) (initOffsetY + event.getY() - touchY);
}
if(scrollableHorizontal){
offsetX = (int) (initOffsetX + event.getX() - touchX);
}
break;
case MotionEvent.ACTION_UP:
if((Math.abs((event.getY() - touchY)) < 10) && ((event.getX() - touchX) < 10)){
System.out.println("Action up");
if (zoomViewClickListener != null) {
zoomViewClickListener.onZoomViewClick(this);
}
}
break;
}
validateOffsets();
return true;
}
private void validateOffsets(){
if (scrollableVertical) {
if (((viewHeight - drawingHeight) / 2 + offsetY) > 0) {
offsetY = (drawingHeight - viewHeight) / 2;
}
if ((viewHeight - drawingHeight) > ((viewHeight - drawingHeight) / 2 + offsetY)) {
offsetY = (viewHeight - drawingHeight) / 2;
}
}
if (scrollableHorizontal) {
if (((viewWidth - drawingWidth) / 2 + offsetX) > 0) {
offsetX = (drawingWidth - viewWidth) / 2;
}
if ((viewWidth - drawingWidth) > ((viewWidth - drawingWidth) / 2 + offsetX)) {
offsetX = (viewWidth - drawingWidth) / 2;
}
}
invalidate();
}
public void zoomIn(){
System.out.println("Zooming In");
if(zoomFactor < 3)
zoomFactor += 0.1;
validateOffsets();
}
public void zoomOut(){
System.out.println("Zooming Out");
if(zoomFactor > 1)
zoomFactor -= 0.1;
validateOffsets();
}
public void setBitmapResource(int id){
image = ((BitmapDrawable)getContext().getResources().getDrawable(id)).getBitmap();
// imgRect = new Rect(0, 0, image.getWidth(), image.getHeight());
ratio = (float)image.getWidth()/image.getHeight();
zoomFactor = 1.0f;
offsetX = 0;
offsetY = 0;
invalidate();
}
}