我正在画布上工作。如下所示，视图类用于缩放和画线。单击缩放按钮时，捏缩放工作正常。但是当我单击绘画按钮时，我将一个布尔值作为真传递，在触摸手指时画线。但是在图像上画线后，我想在图像的特定位置用这条画线再次开始捏缩放（用画线+图像缩放
）
。现在我想在图像 2 上开始捏缩放，如图所示。我尝试搜索但仍然没有任何成功。谢谢
public class DemoView extends View {
private static final float STROKE_WIDTH = 5f;
/** Need to track this so the dirty region can accommodate the stroke. **/
private static final float HALF_STROKE_WIDTH = STROKE_WIDTH / 2;
private Paint paint = new Paint();
private Path path = new Path();
// These matrices will be used to move and zoom image
Matrix matrix = new Matrix();
Matrix savedMatrix = new Matrix();
// We can be in one of these 3 states
static final int NONE = 0;
static final int DRAG = 1;
static final int ZOOM = 0;
public static float xValue;
public static float yValue;
private static final float MAX_ZOOM = 10;
int mode = NONE;
// Remember some things for zooming
PointF start = new PointF();
PointF mid = new PointF();
float oldDist = 1f;
private float globalX;
private float globalY;
private float width;
private float height;
/**
* Optimizes painting by invalidating the smallest possible area.
*/
private float lastTouchX;
private float lastTouchY;
private final RectF dirtyRect = new RectF();
private boolean flag;
private Bitmap bgBitmap;
private float mScaleFactor;
private int mActivePointerId;
private float mPosX;
private float mPosY;
public DemoView(Context context, AttributeSet attrs) {
super(context, attrs);
paint.setAntiAlias(true);
paint.setColor(Color.BLACK);
paint.setStyle(Paint.Style.STROKE);
paint.setStrokeJoin(Paint.Join.ROUND);
paint.setStrokeWidth(STROKE_WIDTH);
bgBitmap = BitmapFactory.decodeResource(context.getResources(), R.drawable.nat);
}
@Override
public void draw(Canvas canvas) {
super.draw(canvas);
canvas.save();
canvas.translate(mPosX, mPosY);
canvas.scale(mScaleFactor, mScaleFactor);
canvas.drawBitmap(bgBitmap, 0,0,null);
if(mScaleFactor != 1.f)
canvas.restore();
if(flag)
canvas.drawPath(path,paint);
if(mScaleFactor == 1.f)
canvas.restore();
}
/**
* Erases the signature.
*/
public void clear() {
path.reset();
// Repaints the entire view.
invalidate();
}
@Override
public boolean onTouchEvent(MotionEvent event) {
float eventX = event.getX();
float eventY = event.getY();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
if (flag) {
path.moveTo(eventX, eventY);
lastTouchX = eventX;
lastTouchY = eventY;
// There is no end point yet, so don't waste cycles invalidating.
return true;
}else{
savedMatrix.set(matrix);
start.set(event.getX(), event.getY());
mode = DRAG;
mActivePointerId = event.getPointerId(0);
break;
}
case MotionEvent.ACTION_POINTER_DOWN:
oldDist = spacing(event);
if (oldDist > 10f) {
savedMatrix.set(matrix);
midPoint(mid, event);
mode = ZOOM;
}
break;
case MotionEvent.ACTION_POINTER_UP:
mode = NONE;
break;
case MotionEvent.ACTION_MOVE:
case MotionEvent.ACTION_UP:
if (flag) {
resetDirtyRect(eventX, eventY);
// When the hardware tracks events faster than they are delivered,
// the
// event will contain a history of those skipped points.
int historySize = event.getHistorySize();
for (int i = 0; i < historySize; i++) {
float historicalX = event.getHistoricalX(i);
float historicalY = event.getHistoricalY(i);
expandDirtyRect(historicalX, historicalY);
path.lineTo(historicalX, historicalY);
}
// After replaying history, connect the line to the touch point.
path.lineTo(eventX, eventY);
break;
}else{
// Start tracking the dirty region.
if (mode == DRAG) {
// ...
matrix.set(savedMatrix);
matrix.postTranslate(event.getX() - start.x, event.getY()
- start.y);
} else if (mode == ZOOM) {
float newDist = spacing(event);
if (newDist > 10f) {
matrix.set(savedMatrix);
float scale = newDist / oldDist;
matrix.postScale(scale, scale, mid.x, mid.y);
}
// final int pointerIndex = event.findPointerIndex((Integer) mActivePointerId);
// final float x = event.getX(pointerIndex);
// final float y = event.getY(pointerIndex);
//
// final float dx = x - globalX;
// final float dy = y - globalY;
// mPosX += dx;
// mPosY += dy;
}
}
default:
Log.e("Ignored touch event: " ,"i"+ event.toString());
return false;
}
// Include half the stroke width to avoid clipping.
invalidate((int) (dirtyRect.left - HALF_STROKE_WIDTH),
(int) (dirtyRect.top - HALF_STROKE_WIDTH),
(int) (dirtyRect.right + HALF_STROKE_WIDTH),
(int) (dirtyRect.bottom + HALF_STROKE_WIDTH));
lastTouchX = eventX;
lastTouchY = eventY;
return true;
}
/**
* Called when replaying history to ensure the dirty region includes all
* points.
*/
private void expandDirtyRect(float historicalX, float historicalY) {
if (historicalX < dirtyRect.left) {
dirtyRect.left = historicalX;
} else if (historicalX > dirtyRect.right) {
dirtyRect.right = historicalX;
}
if (historicalY < dirtyRect.top) {
dirtyRect.top = historicalY;
} else if (historicalY > dirtyRect.bottom) {
dirtyRect.bottom = historicalY;
}
}
/**
* Resets the dirty region when the motion event occurs.
*/
private void resetDirtyRect(float eventX, float eventY) {
// The lastTouchX and lastTouchY were set when the ACTION_DOWN
// motion event occurred.
dirtyRect.left = Math.min(lastTouchX, eventX);
dirtyRect.right = Math.max(lastTouchX, eventX);
dirtyRect.top = Math.min(lastTouchY, eventY);
dirtyRect.bottom = Math.max(lastTouchY, eventY);
}
/** Determine the space between the first two fingers */
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);
}
/** Calculate the mid point of the first 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);
}
public boolean setFlag(boolean b) {
return flag = b;
}
}