Getting coordinates and width/height from a matrix

Question

I'm trying to make a media player for the Android platform and one of the features I'm trying to add is the ability to drag and pinch-zoom pictures.

The problem I'm having is I copied this code from "Hello, Android" ed. 3:

@Override
public boolean onTouch(View v, MotionEvent event) {
ImageView view = (ImageView) v;
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:
    oldDist = spacing(event);
    if (oldDist > 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.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);
        }
    }
    break;
}
view.setImageMatrix(matrix);

This code snippet does exactly what I want, but I need the pure X,Y coordinates and the width/height of the picture instead of the matrix.

Does anyone know how to change the matrix to X, Y coordinates and the width and height?

Answer 1

Turns out the solution is simple:

float[] values = new float[9];
matrix.getValues(values);
globalX = values[Matrix.MTRANS_X];
globalY = values[Matrix.MTRANS_Y];
width = values[Matrix.MSCALE_X]*imageWidth;
height = values[Matrix.MSCALE_Y]*imageHeight;

Answer 2

thanks, i've been looking all night to find this, only one thing: in my example i had to use:

float height = matrixValues[4]*((ImageView)currentView).getDrawable().getIntrinsicHeight();

to get the correct height.

Answer 3

i wrote some methods which may help some users (thanks a lot for the code above!!!):

private void logImageViewMatrixInfos(Matrix matrix, ImageView imageView) {
        float[] values = new float[9];
           matrix.getValues(values);
           float globalX = values[2];
           float globalY = values[5];
           float width = values[0]* imageView.getWidth();
           float height = values[4] * imageView.getHeight();

           Log.i("Log value", "Image Details: xPos: " + globalX + " yPos: " + globalY + "\nwidth: " + width + " height: " + height);
    }

    private float getXValueFromMatrix(Matrix matrix) {

        float[] values = new float[9];
           matrix.getValues(values);
           float globalX = values[2];

           return globalX;
    }

    private float getYValueFromMatrix(Matrix matrix) {

        float[] values = new float[9];
           matrix.getValues(values);
           float globalY = values[5];

           return globalY;
    }

    private float getWidthFromMatrix(Matrix matrix, ImageView imageview) {

        float[] values = new float[9];
           matrix.getValues(values);

           float width = values[0]* imageview.getWidth();

           return width;
    }

    private float getHeightFromMatrix(Matrix matrix, ImageView imageview) {

        float[] values = new float[9];
           matrix.getValues(values);

           float height = values[4] * imageview.getHeight();

           return height;
    }

:=)