如何使用矩阵比例尺中心imageView？

Question

我正在使用Android Studio来显示imageView.我正在使用捏缩放来与我的ImageView进行交互.

码:

private class ScaleListener extends ScaleGestureDetector.SimpleOnScaleGestureListener{
    @Override
    public boolean onScale(ScaleGestureDetector detector) {
        scale = scale * detector.getScaleFactor();
        scale = Math.max(0.1f, Math.min(scale, 5f));
        matrix.setScale(scale, scale);

        imageView.setImageMatrix(matrix);
        return true;
    }
}

@Override
public boolean onTouchEvent(MotionEvent event) {
    scaleGestureDetector.onTouchEvent(event);
    return true;
}

缩放很好,但问题是imageview的位置,它被卡在左上角.尝试布局更改但无关.经过一些研究,我已经在论坛ImageView Center中看到了这些链接与ScaleType矩阵的位置,并在缩放捏合后将图像置于ImageView中,但这些解决方案无法正常工作,我还检查了内部给出的链接.

帮助将不胜感激,

谢谢 !

编辑:添加了关于我如何获得我的ImageView的代码

Picasso.with(this).load(url).resize(350, 330).centerInside().into(imageView);

onCreate Code

ScaleListner类和手势代码

Answer 1

    Picasso.with(this).load(url).into(imageView, new Callback.EmptyCallback() {
        @Override
        public void onSuccess() {
            Drawable d = imageView.getDrawable();
            // TODO: check that d isn't null

            RectF imageRectF = new RectF(0, 0, d.getIntrinsicWidth(), d.getIntrinsicHeight());
            RectF viewRectF = new RectF(0, 0, imageView.getWidth(), imageView.getHeight());
            matrix.setRectToRect(imageRectF, viewRectF, ScaleToFit.CENTER);
            imageView.setImageMatrix(matrix);
        }
    });

编辑2:

如何将图像居中,CENTER_INSIDE但使用矩阵:

首先,我们需要一个带图像尺寸的矩形:

    Drawable d = imageView.getDrawable();
    // TODO: check that d isn't null

    RectF imageRectF = new RectF(0, 0, d.getIntrinsicWidth(), d.getIntrinsicHeight());

接下来,您需要一个具有视图尺寸的矩形:

    RectF viewRectF = new RectF(0, 0, imageView.getWidth(), imageView.getHeight());

现在我们在矩阵上运行一个方法,将图像置于视图中心:

    matrix.setRectToRect(imageRectF, viewRectF, ScaleToFit.CENTER);

这样做是设置矩阵,以便第一个矩形将转换为第二个矩形. ScaleToFit.CENTER将保留纵横比并具有与比例类型相同的效果CENTER_INSIDE.

所以,如果你打电话

    imageView.setImageMatrix(matrix);

此时,您将拥有一个居中的图像.

编辑:我想你差不多了.

您的矩阵将撤消毕加索所做的图像居中,因此您需要在缩放之前进行平移以使图像居中.

    @Override
    public boolean onScale(ScaleGestureDetector detector) {

        Drawable d = imageView.getDrawable();
        // if d is null, then Picasso hasn't loaded the image yet

        float offsetX = (imageView.getWidth() - d.getIntrinsicWidth()) / 2F;
        float offsetY = (imageView.getHeight() - d.getIntrinsicHeight()) / 2F;

        float centerX = imageView.getWidth() / 2F;
        float centerY = imageView.getHeight() / 2F;

        // note that these offset and center values don't change with the scaling, 
        // so you can calculate them somewhere else and then use them here.

        scale *= detector.getScaleFactor();
        scale = Math.max(0.1f, Math.min(scale, 5f));

        matrix.setScale(scale, scale, centerX, centerY);
        matrix.preTranslate(offsetX, offsetY);

        imageView.setImageMatrix(matrix);
    }

你正在使用setScale(float sx, float sy).还有另一个版本,setScale(float sx, float sy, float px, float py)其中px,py是一个支点.

因此,如果要使图像居中,请确定视图的中心,并使用x,y值作为轴心点.

您还需要将图像置于视图中心,因此在缩放之前需要先移动图像.

    float offsetX = (imageView.getWidth() - bitmap.getIntrinsicWidth()) / 2F;
    float offsetY = (imageView.getHeight() - bitmap.getIntrinsicHeight()) / 2F;

    float centerX = imageView.getWidth() / 2F;
    float centerY = imageView.getHeight() / 2F;

    matrix.setScale(scale, scale, centerX, centerY);
    matrix.preTranslate(offsetX, offsetY);