Android 带有触摸事件的画布中的图像
看起来很简单,但我在实现方面遇到了问题 我想要一个屏幕上有图像的画布,包括Android 带有触摸事件的画布中的图像,android,image,android-canvas,ontouchlistener,Android,Image,Android Canvas,Ontouchlistener,看起来很简单,但我在实现方面遇到了问题 我想要一个屏幕上有图像的画布,包括onTouch事件。 我尝试了ImageView,但无法使用canvas。 我尝试了SurfaceView,能够在屏幕上的画布上显示图像,但我在这些事件(缩放、平移)的运动方面遇到了问题 我需要画布,因为我将在代码中渲染图像 有人能告诉我正确的方法吗?你可以用这个: import android.content.Context; import android.graphics.Canvas; import android.
onTouch
事件。
我尝试了ImageView
,但无法使用canvas。
我尝试了SurfaceView
,能够在屏幕上的画布上显示图像,但我在这些事件(缩放、平移)的运动方面遇到了问题
我需要画布,因为我将在代码中渲染图像
有人能告诉我正确的方法吗?你可以用这个:
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.drawable.BitmapDrawable;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.ScaleGestureDetector;
import android.view.View;
public class MyImageView extends View {
private static final int INVALID_POINTER_ID = -1;
private Drawable mImage;
private float mPosX;
private float mPosY;
private float mLastTouchX;
private float mLastTouchY;
private int mActivePointerId = INVALID_POINTER_ID;
private ScaleGestureDetector mScaleDetector;
private float mScaleFactor = 1.f;
public MyImageView(Context context) {
this(context, null, 0);
mImage = getResources().getDrawable(R.drawable.imagename);
mImage.setBounds(0, 0, mImage.getIntrinsicWidth(), mImage.getIntrinsicHeight());
}
public MyImageView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public MyImageView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
mScaleDetector = new ScaleGestureDetector(context, new ScaleListener());
}
@Override
public boolean onTouchEvent(MotionEvent ev) {
// Let the ScaleGestureDetector inspect all events.
mScaleDetector.onTouchEvent(ev);
final int action = ev.getAction();
switch (action & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN: {
final float x = ev.getX();
final float y = ev.getY();
mLastTouchX = x;
mLastTouchY = y;
mActivePointerId = ev.getPointerId(0);
break;
}
case MotionEvent.ACTION_MOVE: {
final int pointerIndex = ev.findPointerIndex(mActivePointerId);
final float x = ev.getX(pointerIndex);
final float y = ev.getY(pointerIndex);
// Only move if the ScaleGestureDetector isn't processing a gesture.
if (!mScaleDetector.isInProgress()) {
final float dx = x - mLastTouchX;
final float dy = y - mLastTouchY;
mPosX += dx;
mPosY += dy;
invalidate();
}
mLastTouchX = x;
mLastTouchY = y;
break;
}
case MotionEvent.ACTION_UP: {
mActivePointerId = INVALID_POINTER_ID;
break;
}
case MotionEvent.ACTION_CANCEL: {
mActivePointerId = INVALID_POINTER_ID;
break;
}
case MotionEvent.ACTION_POINTER_UP: {
final int pointerIndex = (ev.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK)
>> MotionEvent.ACTION_POINTER_INDEX_SHIFT;
final int pointerId = ev.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 = ev.getX(newPointerIndex);
mLastTouchY = ev.getY(newPointerIndex);
mActivePointerId = ev.getPointerId(newPointerIndex);
}
break;
}
}
return true;
}
@Override
public void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.save();
Log.d("DEBUG", "X: "+mPosX+" Y: "+mPosY);
canvas.translate(mPosX, mPosY);
canvas.scale(mScaleFactor, mScaleFactor);
mImage.draw(canvas);
canvas.restore();
}
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));
invalidate();
return true;
}
}
}
您能指出如何在我的活动中使用此自定义视图吗?我已经使用此自定义视图创建了布局,并且在我的活动中设置了ContentView(R.layouts.myImageLayout)。。。猜这还不够吗?调用这个setContentView(newmyImageView(this));&请注意,我已经从MyImageView的构造函数中删除了1个参数。我曾尝试在活动中创建此类的实例,但当绘图命中时,我会得到一个空白屏幕(没有显示图像)。PS:构造函数MyImageView(MapActivity)未定义?哦,代码在我发布注释时没有刷新。。。让我试试现在的作品吧。。。谢谢你对我的热情帮助!祝你一切顺利!