onMatrixChanged() flawed?

[deakjahn]

It calls getDisplayRect() to calculate the display rectangle which in turn uses the drawable intrinsic dimensions. This seems flawed to me. When I try, for instance, with a 700 pixel wide image, I get displayRect.right values well above 1,000 which is clearly wrong. I'll report back with some suggestions shortly but at first sight, the most obvious change would be to map the currently visible rectangle instead of the whole drawable to start with.

[deakjahn]

OK, I can see what's really missing now.

When going in, I can easily supply the scaling and position using setScale(float scale, float focalX, float focalY, boolean animate). But there is no way to get the same three values back, only getScale(). WIth the other two, either reported in onMatrixChanged directly or available for call, we could store and reuse the same values for a repeated display.

[deakjahn]

in PhotoViewAttacher.java:

@Override
public final float getScale() {
  float ScaleX = getValue(mSuppMatrix, Matrix.MSCALE_X);
  float SkewY = getValue(mSuppMatrix, Matrix.MSKEW_Y);
  return (float) Math.sqrt(ScaleX * ScaleX + SkewY * SkewY);
}

public final float getPivotX() {
  return getValue(mSuppMatrix, Matrix.MTRANS_X) / getScale();
}

public final float getPivotY() {
  return getValue(mSuppMatrix, Matrix.MTRANS_Y) / getScale();
}

public final float getRotation() {
  return Math.round(Math.atan2(getValue(mSuppMatrix, Matrix.MSKEW_X), getValue(mSuppMatrix, Matrix.MSCALE_X)) * 180 / Math.PI);
}

And the appropiate overrides in PhotoView.java, as well.

getScale() is just a slightly faster version of the original.

[danielesegato]

@deakjahn I've tried your code even if it didn't make much sense to me...

    float originalScale = mAttacher.getScale();
    float scale = Math.max(mAttacher.getMinimumScale(), Math.min(originalScale, mAttacher.getMaximumScale()));
    float[] matrixValue = new float[9];
    mAttacher.getDisplayMatrix().getValues(matrixValue);
    float focalX = matrixValue[Matrix.MTRANS_X] / originalScale;
    float focalY = matrixValue[Matrix.MTRANS_Y] / originalScale;

I save this values and then restore them later using:

        mAttacher.setScale(mImageScale, mImageFocalX, mImageFocalY, view.getWindowToken() != null);

The originalScale is sometimes slightly higher then the max scale, this is the reason I capped it.

Anyway this code doesn't work cause the focal point are plainly wrong.

I did some test and I think the TRANS_X / TRANS_Y give a measure of the distance between the top-left of the image and the top-left of the screen.

Which means it's not the focal point.

I understood the focal point to be the "center" point of the image that should be showed in the screen..

But I'm probably wrong cause I manually set a specific pixel in an image as focal point (with 3x zoom) and I ended up near that point but the image wasn't centered there.

I still didn't understood what should the focal point be and thus how to properly extract it from the Attacher.