使用ImageView的变换矩阵，而不是canvas.scale（浮球，浮球，浮球，浮球） [英] Using an ImageView transform matrix instead of canvas.scale(float, float, float, float)

问题描述

我需要改变的方式，我缩放和我的ImageView转向使用矩阵而不是调用 canvas.scale（,,,,），但我想不通出正确调用做到这一点。

I need to change the way I am scaling and moving my imageview to using a matrix instead of calling canvas.scale(,,,,), but I cannot figure out the proper calls to do this.

我这在我的 ScaleListener 监听器类的 onScale 法

I had this in my ScaleListener listener class's onScale method

public boolean onScale(ScaleGestureDetector detector) {

    ...//determining zoom level and pivot points offset

    child.zoom(scaleFactor, zoomCenter[0], zoomCenter[1]);
}

我在孩子的ImageView 的onDraw 方法：

I had in the child ImageView's onDraw method:

protected void onDraw(Canvas canvas){

    super.onDraw(canvas);
    canvas.scale(mScaleFactor, mScaleFactor, mPosX, mPosY);
    ...
    //do all the drawing here
}

public void zoom(float scaleFactor, float zoomCenterX, float zoomCenterY) {
    mScaleFactor = scaleFactor;
    mPosX = zoomCenterX;
    mPosY = zoomCenterY;

    //redraw and remeasure the mapview after zooming in
    invalidate();

}

我想在 onScale 方法是这样的：

public boolean onScale(ScaleGestureDetector detector) {
        ...//calculating scale and offsets

        Matrix m = child.getImageMatrix();
        m.reset();
        m.postScale(scaleFactor, scaleFactor);
        m.postTranslate(zoomCenter[0], zoomCenter[1]);
        child.setScaleType(ScaleType.MATRIX);
        child.setImageMatrix(m);

        child.invalidate();


        return true;
    }

但是，这似乎并没有做任何事......我在这里失去了一些东西？我试着用 child.getMatrix（）来代替，但通过一个IllegalStateException称矩阵不能修改。任何帮助将是巨大的！

But this does not appear to be doing anything...am I missing something here? I tried using child.getMatrix() instead but that through an IllegalStateException saying the matrix cannot be modified. Any help would be great!

推荐答案

好吧，我想通了什么问题了。我使用 setImageMatrix（M）来应用到整个ImageView的子类，而不是设置的矩阵画布，像这样的：

Okay I figured out what the problem was. I was using setImageMatrix(m) to apply to the entire ImageView child class, instead of setting the matrix for the canvas, like this:

@Override
protected void onDraw(Canvas canvas){

    ...
    canvas.concat(transform);

}

我不知道有什么区别，两者之间虽然，如果有人知道看<一个href=\"http://stackoverflow.com/questions/18408401/what-is-the-difference-between-view-getmatrix-and-imageview-getimagematrix\">difference bewteen imageMatrix和基质

I'm not sure what the difference is between the two though, if anyone knows see difference bewteen imageMatrix and matrix

修改：使用 canvas.setMatrix（变换）搞砸滚动; canvas.concat（变换）建议，而不是和做这一招

EDIT: using canvas.setMatrix(transform) messed up the scrolling; canvas.concat(transform) was recommended instead and that does this trick

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