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所以我一直在試圖創建一個程序，可以拖動，縮放和旋轉照片。我似乎遇到的一個大問題是，每當我嘗試旋轉照片時，它都會沿着角落旋轉，而不是圍繞中心旋轉。這意味着當我嘗試旋轉圖像時，它會很快離開我的手指。每當我嘗試旋轉imageview，它只能在軸上旋轉
我遇到的另一個大問題是，每次用兩根手指觸摸時，圖像都會重置爲完全直立，而不是我觸摸時保持的角度。
@Override
protected void onDraw(Canvas canvas) {
canvas.save();
//if(mode==DRAG)
canvas.translate(mPosX, mPosY);
if (myScale.isInProgress()) {
canvas.scale(mScaleFactor, mScaleFactor, myScale.getFocusX(), myScale.getFocusY());
}
else{
canvas.scale(mScaleFactor, mScaleFactor, mLastGestureX, mLastGestureY);
}
if (myScale.isInProgress()) {
canvas.rotate(degrees, myScale.getFocusX(), myScale.getFocusY());
}
else{
canvas.rotate(degrees, mLastGestureX, mLastGestureY);
}
//canvas.setMatrix(matrix);
//setImageMatrix(matrix);
super.onDraw(canvas);
canvas.restore();
//canvas.drawBitmap(,matrix,new Paint());
}
@Override
public boolean onTouchEvent(MotionEvent event) {
super.onTouchEvent(event);
if(event.getPointerCount()>1){
myScale.onTouchEvent(event);
}
switch (event.getAction() & MotionEvent.ACTION_MASK){
case MotionEvent.ACTION_DOWN: {
savedMatrix.set(matrix);
final float x = event.getX();
final float y = event.getY();
mode=DRAG;
// Remember where we started
mLastTouchX = x;
mLastTouchY = y;
mActivePointerId = event.getPointerId(0);
lastEvent = null;
break;
}
case MotionEvent.ACTION_POINTER_DOWN: {
oldDist = spacing(event);
//savedMatrix.set(matrix);
//midPoint(mid, event);
Log.d("touchResponse: ", "mode=ZOOM");
final float gx = myScale.getFocusX();
final float gy = myScale.getFocusY();
mLastGestureX=gx;
mLastGestureY=gy;
mode=ZOOM;
lastEvent = new float[4];
lastEvent[0] = event.getX(0);
lastEvent[1] = event.getX(1);
lastEvent[2] = event.getY(0);
lastEvent[3] = event.getY(1);
d = rotation(event);
break;
}
case MotionEvent.ACTION_MOVE: {
final int pointerIndex = event.findPointerIndex(mActivePointerId);
final float x = event.getX(pointerIndex);
final float y = event.getY(pointerIndex);
// Calculate the distance moved
if(!myScale.isInProgress()&&mode==DRAG){
// Move the object
float dx = x-mLastTouchX;
float dy = y-mLastTouchY;
mPosX+=dx;
mPosY+=dy;
// Remember this touch position for the next move event
// Invalidate to request a redraw
invalidate();
}
mLastTouchX = x;
mLastTouchY = y;
if(event.getPointerCount()==2){
if (lastEvent!=null){
newRot=rotation(event);
degrees = newRot-d;
}
}
invalidate();
break;
}
case MotionEvent.ACTION_UP: {
}
case MotionEvent.ACTION_POINTER_UP: {
// Extract the index of the pointer that left the touch sensor\
mode=NONE;
mode = NONE;
lastEvent = null;
final int pointerIndex = (event.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK)
>> MotionEvent.ACTION_POINTER_INDEX_SHIFT;
final int pointerId = event.getPointerId(pointerIndex);
if (pointerId == mActivePointerId) {
// This was our active pointer going up. Choose a new
// active pointer and adjust accordingly.
final int newPointerIndex = pointerIndex == 0 ? 1 : 0;
mLastTouchX = event.getX(newPointerIndex);
mLastTouchY = event.getY(newPointerIndex);
mActivePointerId = event.getPointerId(newPointerIndex);
}
invalidate();
break;
}
}
return true;
}
//this is a method i ripped from a tutoriaql
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);
}
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);
}
private class ScaleListener extends ScaleGestureDetector.SimpleOnScaleGestureListener {
@Override
public boolean onScale(ScaleGestureDetector detector) {
mScaleFactor *= detector.getScaleFactor();
// Don't let the object get too small or too large.
mScaleFactor = Math.max(0.1f, Math.min(mScaleFactor, 10.0f));
//matrix=temp;
invalidate();
return true;
}
}
private float rotation(MotionEvent event) {
double delta_x = (event.getX(0) - event.getX(1));
double delta_y = (event.getY(0) - event.getY(1));
double radians = Math.atan2(delta_y, delta_x);
//if (Constant.TRACE) Log.d("Rotation ~~~~~~~~~~~~~~~~~", delta_x+" ## "+delta_y+" ## "+radians+" ## "
// +Math.toDegrees(radians));
Log.d("Rotation ~~~~~~~~~~~~~~~~~", delta_x+" ## "+delta_y+" ## "+radians+" ## "
+Math.toDegrees(radians));
return (float) Math.toDegrees(radians);
}