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An ImageView with modified onMeasure which scales bounding box even if ImageView has layout width/height match_parent / fill_parent
package nilzor.public.views;
import android.content.Context;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.util.Log;
import android.widget.ImageView;
public class ScalingImageView extends ImageView {
private boolean mAdjustViewBounds;
private int mMaxWidth;
private int mMaxHeight;
public ScalingImageView(Context context) {
super(context);
}
public ScalingImageView(Context context, AttributeSet attrs) {
super(context, attrs);
}
@Override
// getAdjustViewBounds() was added in api level 16, so for backwards compatibility sake...
public void setAdjustViewBounds(boolean adjustViewBounds) {
super.setAdjustViewBounds(adjustViewBounds);
mAdjustViewBounds = adjustViewBounds;
}
@Override
public void setMaxWidth(int maxWidth) {
super.setMaxWidth(maxWidth);
mMaxWidth = maxWidth;
}
@Override
public void setMaxHeight(int maxHeight) {
super.setMaxHeight(maxHeight);
mMaxHeight = maxHeight;
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
Drawable mDrawable = getDrawable();
int mDrawableWidth = mDrawable.getIntrinsicWidth();
int mDrawableHeight = mDrawable.getIntrinsicHeight();
//------------
int w;
int h;
// Desired aspect ratio of the view's contents (not including padding)
float desiredAspect = 0.0f;
// We are allowed to change the view's width
boolean resizeWidth = false;
// We are allowed to change the view's height
boolean resizeHeight = false;
final int widthSpecMode = MeasureSpec.getMode(widthMeasureSpec);
final int heightSpecMode = MeasureSpec.getMode(heightMeasureSpec);
final int actualWidth = MeasureSpec.getSize(widthMeasureSpec);
final int actualHeight = MeasureSpec.getSize(heightMeasureSpec);
if (mDrawable == null) {
// If no drawable, its intrinsic size is 0.
mDrawableWidth = -1;
mDrawableHeight = -1;
w = h = 0;
} else {
w = mDrawableWidth;
h = mDrawableHeight;
if (w <= 0) w = 1;
if (h <= 0) h = 1;
// We are supposed to adjust view bounds to match the aspect
// ratio of our drawable. See if that is possible.
desiredAspect = (float) w / (float) h;
if (mAdjustViewBounds) {
// Original Android code setting whether to resizeHeight / width.
/* resizeWidth = widthSpecMode != MeasureSpec.EXACTLY;
resizeHeight = heightSpecMode != MeasureSpec.EXACTLY; */
// Modified code which resizes no matter what MeasureSpec is set to. Works better with fill_parent/match_parent.
float actualAspect = (float) actualWidth/ (float) actualHeight;
if (actualAspect > desiredAspect) resizeWidth = true;
else if (actualAspect < desiredAspect) resizeHeight = true;
}
}
int pleft = getPaddingLeft();
int pright = getPaddingRight();
int ptop = getPaddingTop();
int pbottom = getPaddingBottom();
int widthSize;
int heightSize;
if (resizeWidth || resizeHeight) {
/* If we get here, it means we want to resize to match the
drawables aspect ratio, and we have the freedom to change at
least one dimension.
*/
// Get the max possible width given our constraints
widthSize = resolveAdjustedSize(w + pleft + pright, mMaxWidth, widthMeasureSpec);
// Get the max possible height given our constraints
heightSize = resolveAdjustedSize(h + ptop + pbottom, mMaxHeight, heightMeasureSpec);
if (desiredAspect != 0.0f) {
// See what our actual aspect ratio is
float actualAspect = (float)(widthSize - pleft - pright) /
(heightSize - ptop - pbottom);
if (Math.abs(actualAspect - desiredAspect) > 0.0000001) {
boolean done = false;
// Try adjusting width to be proportional to height
if (resizeWidth) {
int newWidth = (int)(desiredAspect * (heightSize - ptop - pbottom)) +
pleft + pright;
if (newWidth <= widthSize) {
widthSize = newWidth;
done = true;
}
}
// Try adjusting height to be proportional to width
if (!done && resizeHeight) {
int newHeight = (int)((widthSize - pleft - pright) / desiredAspect) +
ptop + pbottom;
if (newHeight <= heightSize) {
heightSize = newHeight;
}
}
}
}
} else {
/* We are either don't want to preserve the drawables aspect ratio,
or we are not allowed to change view dimensions. Just measure in
the normal way.
*/
w += pleft + pright;
h += ptop + pbottom;
w = Math.max(w, getSuggestedMinimumWidth());
h = Math.max(h, getSuggestedMinimumHeight());
widthSize = resolveSizeAndState(w, widthMeasureSpec, 0);
heightSize = resolveSizeAndState(h, heightMeasureSpec, 0);
}
Log.i("F&C", "Setting dimen " + widthSize + " x " + heightSize + " for " +getId() + " Adjusted w/h:" + resizeWidth + "/" + resizeHeight);
setMeasuredDimension(widthSize, heightSize);
}
private int resolveAdjustedSize(int desiredSize, int maxSize,
int measureSpec) {
int result = desiredSize;
int specMode = MeasureSpec.getMode(measureSpec);
int specSize = MeasureSpec.getSize(measureSpec);
switch (specMode) {
case MeasureSpec.UNSPECIFIED:
/* Parent says we can be as big as we want. Just don't be larger
than max size imposed on ourselves.
*/
result = Math.min(desiredSize, maxSize);
break;
case MeasureSpec.AT_MOST:
// Parent says we can be as big as we want, up to specSize.
// Don't be larger than specSize, and don't be larger than
// the max size imposed on ourselves.
result = Math.min(Math.min(desiredSize, specSize), maxSize);
break;
case MeasureSpec.EXACTLY:
// No choice. Do what we are told.
result = specSize;
break;
}
return result;
}
}
@Nilzor
Owner

I have only changed two "business lines" of code from the original code of Android v17's onMeasure(). I had to do some hacks in order to get it compile though, as a lot of private variables and methods (resolveAdjustedSize) were used.

@kramer65

I'm using Picasso (http://square.github.io/picasso/) to load an image from a URL. Because of this mDrawable.getIntrinsicWidth() returns a NullPointer. Would anybody have an idea how this could be solved (maybe by only measuring the IntrinsicWidth once the image has been received by Picasso)?

All tips are welcome!

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