我的Activity中有一个ImageView和一个surfaceView。我想使用多点触控移动（拖动）并调整imageView的大小。所以，这是touchListener类：
private final class MyTouchListener implements View.OnTouchListener {
private static final int NONE = 0;
private static final int DRAG = 1;
private static final int ZOOM = 2;
private static final float MIN_ZOOM = 0.5f;
private static final float MAX_ZOOM = 5f;
private Matrix matrix;
private Matrix savedMatrix = new Matrix();
private PointF start = new PointF();
private PointF mid = new PointF();
private int mode = NONE;
private float oldDistance = 1f;
private float dx; // postTranslate X distance
private float dy; // postTranslate Y distance
private float[] matrixValues = new float[9];
float matrixX = 0; // X coordinate of matrix inside the ImageView
float matrixY = 0; // Y coordinate of matrix inside the ImageView
float width = 0; // width of drawable
float height = 0; // height of drawable
private MyTouchListener (Matrix m){
this.matrix = m;
}
public boolean onTouch(View view, MotionEvent event) {
ImageView imageView = (ImageView)view;
switch(event.getAction() & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN:
savedMatrix.set(matrix);
start.set(event.getX(), event.getY());
mode = DRAG;
break;
case MotionEvent.ACTION_POINTER_DOWN:
oldDistance = spacing(event);
if(oldDistance > 10f) {
savedMatrix.set(matrix);
midPoint(mid, event);
mode = ZOOM;
}
break;
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_POINTER_UP:
mode = NONE;
break;
case MotionEvent.ACTION_MOVE:
if(mode == DRAG) {
matrix.set(savedMatrix);
matrix.getValues(matrixValues);
matrixX = matrixValues[2];
matrixY = matrixValues[5];
width = matrixValues[0] * (((ImageView) view).getDrawable()
.getIntrinsicWidth());
height = matrixValues[4] * (((ImageView) view).getDrawable()
.getIntrinsicHeight());
dx = event.getX() - start.x;
dy = event.getY() - start.y;
//if image will go outside left bound
if (matrixX + dx < 0){
dx = -matrixX;
}
//if image will go outside right bound
if(matrixX + dx + width > view.getWidth()){
dx = view.getWidth() - matrixX - width;
}
//if image will go oustside top bound
if (matrixY + dy < 0){
dy = -matrixY;
}
//if image will go outside bottom bound
if(matrixY + dy + height > view.getHeight()){
dy = view.getHeight() - matrixY - height;
}
matrix.postTranslate(dx, dy);
}
else if(mode == ZOOM) {
float newDistance = spacing(event);
if(newDistance > 10f) {
matrix.set(savedMatrix);
float scale = newDistance / oldDistance;
float[] values = new float[9];
matrix.getValues(values);
float currentScaleX = values[Matrix.MSCALE_X];
float currentScaleY = values[Matrix.MSCALE_X];
if(scale * currentScaleX > MAX_ZOOM)
scale = MAX_ZOOM / currentScaleX;
else if (scale * currentScaleX < MIN_ZOOM)
scale = MIN_ZOOM / currentScaleX;
matrix.postScale(scale, scale, mid.x, mid.y);
}
}
break;
}
imageView.setImageMatrix(matrix);
return true;
}
private float spacing(MotionEvent event) {
float x = event.getX(0) - event.getX(1);
float y = event.getY(0) - event.getY(1);
return (float) Math.sqrt(x * x + y * y);
}
private void midPoint(PointF point, MotionEvent event) {
point.set((event.getX(0) + event.getX(1)) / 2, (event.getY(0) + event.getY(1)) / 2);
}
}
问题是当我调整图像大小时，没有模仿，而且屏幕尺寸会变大。
答案 0 :(得分：1)
首先，您需要显示图像的视图的宽度和高度。您可能需要将其传递给MyTouchListener。
之后，当您调整缩放时，只需添加更多级别的检查，如下所示：
Drawable imageDrawable = imageView.getDrawable();
// Checks if current scale would cause the image to get bigger than its container
if (imageDrawable.getIntrinsicWidth() * scale > containerViewWidth
|| imageDrawable.getIntrinsicHeight() * scale > containerViewHeight) {
// Gets the minimal scale that prevents the overflow in zoom
scale = Math.min(targetViewWidth/imageDrawable.getIntrinsicWidth(),
targetViewHeight/imageDrawable.getIntrinsicHeight());
}
if (scale * currentScaleX > MAX_ZOOM) {
scale = MAX_ZOOM / currentScaleX;
} else if (scale * currentScaleX < MIN_ZOOM) {
scale = MIN_ZOOM / currentScaleX;
}
答案 1 :(得分：0)
使用此代码为自定义图像视图创建一个类：
import android.content.Context;
import android.graphics.Matrix;
import android.graphics.PointF;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.ScaleGestureDetector;
import android.view.View;
import android.widget.ImageView;
public class TouchImageView extends ImageView {
Matrix matrix;
// We can be in one of these 3 states
static final int NONE = 0;
static final int DRAG = 1;
static final int ZOOM = 2;
int mode = NONE;
// Remember some things for zooming
PointF last = new PointF();
PointF start = new PointF();
float minScale = 1f;
float maxScale = 3f;
float[] m;
int viewWidth, viewHeight;
static final int CLICK = 3;
float saveScale = 1f;
protected float origWidth, origHeight;
int oldMeasuredWidth, oldMeasuredHeight;
ScaleGestureDetector mScaleDetector;
Context context;
public TouchImageView(Context context) {
super(context);
sharedConstructing(context);
}
public TouchImageView(Context context, AttributeSet attrs) {
super(context, attrs);
sharedConstructing(context);
}
private void sharedConstructing(Context context) {
super.setClickable(true);
this.context = context;
mScaleDetector = new ScaleGestureDetector(context, new ScaleListener());
matrix = new Matrix();
m = new float[9];
setImageMatrix(matrix);
setScaleType(ScaleType.MATRIX);
setOnTouchListener(new OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
mScaleDetector.onTouchEvent(event);
PointF curr = new PointF(event.getX(), event.getY());
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
last.set(curr);
start.set(last);
mode = DRAG;
break;
case MotionEvent.ACTION_MOVE:
if (mode == DRAG) {
float deltaX = curr.x - last.x;
float deltaY = curr.y - last.y;
float fixTransX = getFixDragTrans(deltaX, viewWidth,
origWidth * saveScale);
float fixTransY = getFixDragTrans(deltaY, viewHeight,
origHeight * saveScale);
matrix.postTranslate(fixTransX, fixTransY);
fixTrans();
last.set(curr.x, curr.y);
}
break;
case MotionEvent.ACTION_UP:
mode = NONE;
int xDiff = (int) Math.abs(curr.x - start.x);
int yDiff = (int) Math.abs(curr.y - start.y);
if (xDiff < CLICK && yDiff < CLICK)
performClick();
break;
case MotionEvent.ACTION_POINTER_UP:
mode = NONE;
break;
}
setImageMatrix(matrix);
invalidate();
return true; // indicate event was handled
}
});
}
public void setMaxZoom(float x) {
maxScale = x;
}
private class ScaleListener extends
ScaleGestureDetector.SimpleOnScaleGestureListener {
@Override
public boolean onScaleBegin(ScaleGestureDetector detector) {
mode = ZOOM;
return true;
}
@Override
public boolean onScale(ScaleGestureDetector detector) {
float mScaleFactor = detector.getScaleFactor();
float origScale = saveScale;
saveScale *= mScaleFactor;
if (saveScale > maxScale) {
saveScale = maxScale;
mScaleFactor = maxScale / origScale;
} else if (saveScale < minScale) {
saveScale = minScale;
mScaleFactor = minScale / origScale;
}
if (origWidth * saveScale <= viewWidth
|| origHeight * saveScale <= viewHeight)
matrix.postScale(mScaleFactor, mScaleFactor, viewWidth / 2,
viewHeight / 2);
else
matrix.postScale(mScaleFactor, mScaleFactor,
detector.getFocusX(), detector.getFocusY());
fixTrans();
return true;
}
}
void fixTrans() {
matrix.getValues(m);
float transX = m[Matrix.MTRANS_X];
float transY = m[Matrix.MTRANS_Y];
float fixTransX = getFixTrans(transX, viewWidth, origWidth * saveScale);
float fixTransY = getFixTrans(transY, viewHeight, origHeight
* saveScale);
if (fixTransX != 0 || fixTransY != 0)
matrix.postTranslate(fixTransX, fixTransY);
}
float getFixTrans(float trans, float viewSize, float contentSize) {
float minTrans, maxTrans;
if (contentSize <= viewSize) {
minTrans = 0;
maxTrans = viewSize - contentSize;
} else {
minTrans = viewSize - contentSize;
maxTrans = 0;
}
if (trans < minTrans)
return -trans + minTrans;
if (trans > maxTrans)
return -trans + maxTrans;
return 0;
}
float getFixDragTrans(float delta, float viewSize, float contentSize) {
if (contentSize <= viewSize) {
return 0;
}
return delta;
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
viewWidth = MeasureSpec.getSize(widthMeasureSpec);
viewHeight = MeasureSpec.getSize(heightMeasureSpec);
//
// Rescales image on rotation
//
if (oldMeasuredHeight == viewWidth && oldMeasuredHeight == viewHeight
|| viewWidth == 0 || viewHeight == 0)
return;
oldMeasuredHeight = viewHeight;
oldMeasuredWidth = viewWidth;
if (saveScale == 1) {
// Fit to screen.
float scale;
Drawable drawable = getDrawable();
if (drawable == null || drawable.getIntrinsicWidth() == 0
|| drawable.getIntrinsicHeight() == 0)
return;
int bmWidth = drawable.getIntrinsicWidth();
int bmHeight = drawable.getIntrinsicHeight();
Log.d("bmSize", "bmWidth: " + bmWidth + " bmHeight : " + bmHeight);
float scaleX = (float) viewWidth / (float) bmWidth;
float scaleY = (float) viewHeight / (float) bmHeight;
scale = Math.min(scaleX, scaleY);
matrix.setScale(scale, scale);
// Center the image
float redundantYSpace = (float) viewHeight
- (scale * (float) bmHeight);
float redundantXSpace = (float) viewWidth
- (scale * (float) bmWidth);`enter code here`
redundantYSpace /= (float) 2;
redundantXSpace /= (float) 2;
matrix.postTranslate(redundantXSpace, redundantYSpace);
origWidth = viewWidth - 2 * redundantXSpace;
origHeight = viewHeight - 2 * redundantYSpace;
setImageMatrix(matrix);
}
fixTrans();
}
}
现在使用xml：
<(your package name).TouchImageView
android:id="@+id/imgDisplay"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:scaleType="fitCenter" />
现在你可以像这样使用它：
imgDisplay = (TouchImageView) viewLayout.findViewById(R.id.imgDisplay);
Bitmap bitmap = BitmapFactory.decodeFile(_imagePaths.get(position), options);
imgDisplay.setImageBitmap(bitmap);