[Android] ScalableImageView

/*
 * Stan 2013/04/25
 * ver 2.0.8
 */
package com.stan.libs.imageview.scalable;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Matrix;
import android.graphics.PointF;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.ScaleGestureDetector;
import android.view.View;
import android.widget.ImageView;

/*
 * @author: Stan
 */
public class StanScalableImageView extends ImageView {

private Matrix matrix = new Matrix();

// mode can be in one of these 3 states
private static final int NONE = 0;
private static final int DRAG = 1;
private static final int ZOOM = 2;
private int mode = NONE;

private static final int CLICK = 3;

// Remember some things
private PointF last = new PointF();
private PointF start = new PointF();
private float minScale = 1f;// default
private float maxScale = 3f;// default
private float minScaleTemp;// measure
private float maxScaleTemp;// measure
private float[] m;
private float redundantXSpace, redundantYSpace;
private float width, height;
private float nowScale = 1f;
private float origWidth, origHeight, imageWidth, imageHeight,
redundantWidth, redundantHeight;
private boolean fit = false;

private ScaleGestureDetector mScaleDetector;

public StanScalableImageView(Context context) {
super(context);
initStanScalableImageView(context);
}

public StanScalableImageView(Context context, AttributeSet attrs) {
super(context, attrs);
initStanScalableImageView(context);
}

public StanScalableImageView(Context context, AttributeSet attrs,
int defStyle) {
super(context, attrs, defStyle);
initStanScalableImageView(context);
}

private void initStanScalableImageView(Context context) {
super.setScaleType(ScaleType.CENTER);
mScaleDetector = new ScaleGestureDetector(context, new ScaleListener());
matrix.setTranslate(1f, 1f);
m = new float[9];
setImageMatrix(matrix);
setScaleType(ScaleType.MATRIX);
setOnTouchListener(new DragListener());
}

@Override
public void setImageBitmap(Bitmap bitmap) {
super.setImageBitmap(bitmap);
imageWidth = bitmap.getWidth();
imageHeight = bitmap.getHeight();
}

@Override
public void setImageDrawable(Drawable drawable) {
super.setImageDrawable(drawable);
imageWidth = drawable.getIntrinsicWidth();
imageHeight = drawable.getIntrinsicHeight();
}

@Override
public void setImageResource(int resourceID) {
super.setImageResource(resourceID);
imageWidth = getResources().getDrawable(resourceID).getIntrinsicWidth();
imageHeight = getResources().getDrawable(resourceID)
.getIntrinsicHeight();
}

public void setMaxZoom(float x) {
this.maxScale = x;
}

public void setMinZoom(float x) {
this.minScale = x;
}

public void setFit(boolean fit) {
this.fit = fit;
}

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
width = MeasureSpec.getSize(widthMeasureSpec);
height = MeasureSpec.getSize(heightMeasureSpec);
float scale;
if (fit) {
float scaleX = (float) width / (float) imageWidth;
float scaleY = (float) height / (float) imageHeight;
scale = Math.min(scaleX, scaleY);
matrix.setScale(scale, scale);
} else {
scale = 1;
}
minScaleTemp = minScale * scale;
maxScaleTemp = maxScale * scale;

setImageMatrix(matrix);
nowScale = scale;

// Center the image
redundantHeight = (scale * (float) imageHeight);
redundantWidth = (scale * (float) imageWidth);
redundantYSpace = (float) height - (scale * (float) imageHeight);
redundantXSpace = (float) width - redundantWidth;
redundantYSpace /= (float) 2;
redundantXSpace /= (float) 2;

matrix.getValues(m);
float x = m[Matrix.MTRANS_X];
float y = m[Matrix.MTRANS_Y];
matrix.postTranslate(redundantXSpace - x, redundantYSpace - y);

origWidth = width - 2 * redundantXSpace;
origHeight = height - 2 * redundantYSpace;
setImageMatrix(matrix);
}

private class DragListener implements OnTouchListener {

@Override
public boolean onTouch(View v, MotionEvent event) {
mScaleDetector.onTouchEvent(event);
matrix.getValues(m);
float x = m[Matrix.MTRANS_X];
float y = m[Matrix.MTRANS_Y];
PointF curr = new PointF(event.getX(), event.getY());

switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
last.set(event.getX(), event.getY());
start.set(last);
if (nowScale * imageWidth > width * 1.05
|| nowScale * imageHeight > height * 1.05) {
mode = DRAG;
}
break;
case MotionEvent.ACTION_MOVE:
float deltaX = curr.x - last.x;
float deltaY = curr.y - last.y;
if (mode == DRAG) {
float scaleWidth = Math.round(imageWidth * nowScale);
float scaleHeight = Math.round(imageHeight * nowScale);
// x
if (scaleWidth < width) {
deltaX = redundantXSpace - x
- (imageWidth * nowScale - redundantWidth) / 2;
} else {
if (deltaX > 0 && x + deltaX > 0) {
deltaX = -x;
} else if (deltaX < 0
&& x + deltaX + scaleWidth < width) {
deltaX = width - x - scaleWidth;
}
}
// y
if (scaleHeight < height) {
deltaY = redundantYSpace - y
- (imageHeight * nowScale - redundantHeight)
/ 2;
} else {
if (deltaY > 0 && y + deltaY > 0) {
deltaY = -y;
} else if (deltaY < 0
&& y + deltaY + scaleHeight < height) {
deltaY = height - y - scaleHeight;
}
}
matrix.postTranslate(deltaX, deltaY);
last.set(curr.x, curr.y);
}
break;

case MotionEvent.ACTION_UP:
mode = NONE;
int xDiff = (int) Math.abs(curr.x - start.x);
int yDiff = (int) Math.abs(curr.y - start.y);
if (xDiff < CLICK && yDiff < CLICK)
performClick();
break;

case MotionEvent.ACTION_POINTER_UP:
mode = NONE;
break;
}
setImageMatrix(matrix);
invalidate();
return true;
}
}

private class ScaleListener extends
ScaleGestureDetector.SimpleOnScaleGestureListener {
@Override
public boolean onScaleBegin(ScaleGestureDetector detector) {
mode = ZOOM;
last.set(detector.getFocusX(), detector.getFocusY());
start.set(last);
return true;
}

@Override
public boolean onScale(ScaleGestureDetector detector) {
float mScaleFactor = detector.getScaleFactor();
float origScale = nowScale;
nowScale *= mScaleFactor;
if (nowScale > maxScaleTemp) {
nowScale = maxScaleTemp;
mScaleFactor = maxScaleTemp / origScale;
} else if (nowScale < minScaleTemp) {
nowScale = minScaleTemp;
mScaleFactor = minScaleTemp / origScale;
}
if (origWidth * nowScale <= width
|| origHeight * nowScale <= height) {
matrix.postScale(mScaleFactor, mScaleFactor, width / 2,
height / 2);
} else {
matrix.postScale(mScaleFactor, mScaleFactor,
detector.getFocusX(), detector.getFocusY());
}
matrix.getValues(m);
float x = m[Matrix.MTRANS_X];
float y = m[Matrix.MTRANS_Y];
float scaleWidth = Math.round(imageWidth * nowScale);
float scaleHeight = Math.round(imageHeight * nowScale);
if (nowScale < origScale) {
if (x > 0 && x + scaleWidth > width) {
matrix.postTranslate(-x, 0);
} else if (x < 0 && x + scaleWidth < width) {
matrix.postTranslate(width - x - scaleWidth, 0);
} else if (x > 0 && x + scaleWidth < width) {
matrix.postTranslate((width - scaleWidth) / 2 - x, 0);
}
if (y > 0 && y + scaleHeight > height) {
matrix.postTranslate(0, -y);
} else if (y < 0 && y + scaleHeight < height) {
matrix.postTranslate(0, height - y - scaleHeight);
} else if (y > 0 && y + scaleHeight < height) {
matrix.postTranslate(0, (height - scaleHeight) / 2 - y);
}
}

PointF curr = new PointF(detector.getFocusX(), detector.getFocusY());
float deltaX = curr.x - last.x;
float deltaY = curr.y - last.y;
last.set(curr.x, curr.y);
// x
if (scaleWidth < width) {
deltaX = redundantXSpace - x
- (imageWidth * nowScale - redundantWidth) / 2;
return true;
} else {
if (deltaX > 0 && x + deltaX > 0) {
deltaX = -x;
} else if (deltaX < 0 && x + deltaX + scaleWidth < width) {
deltaX = width - x - scaleWidth;
}
}
// y
if (scaleHeight < height) {
deltaY = redundantYSpace - y
- (imageHeight * nowScale - redundantHeight) / 2;
return true;
} else {
if (deltaY > 0 && y + deltaY > 0) {
deltaY = -y;
} else if (deltaY < 0 && y + deltaY + scaleHeight < height) {
deltaY = height - y - scaleHeight;
}
}
matrix.postTranslate(deltaX, deltaY);
return true;
}
}
}