Android的图像缩放活动 [英] Image zoom activity for android
本文介绍了Android的图像缩放活动的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我正在尝试实现双击和缩小缩放活动.我为第一个编写了一些代码，但是似乎不起作用(我现在只能将android仿真器用于eclipse.所以我不确定我的结果是否正确)
I'm trying to implement the double tap and the pinch to zoom activity. I wrote some code for the first one but it seem not to work (i can use only the android emulator for eclipse for now. So I'm not sure if my result is the right one)
无论如何，我无法理解我在做什么错.我肯定会忘记一些东西.
Anyway I'm not able to understand what am I doing wrong. I'm surely forgetting something.
这是我的代码:
public class ImageZoomView extends View implements OnGestureListener {
private static final int SCALING_FACTOR = 50;
private final int LANDSCAPE = 1;
private GestureDetector gestureDetector;
private Drawable image = null;
private int scalefactor = 0;
private int orientation;
private int zoomCtr = 0;
private long lastTouchTime = 0;
private int winX, winY, imageX, imageY, scrollX = 0, scrollY = 0, left,
top, bottom, right;
public ImageZoomView(Context context, int orientation) {
super(context);
setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT,
LayoutParams.FILL_PARENT));
this.orientation = orientation;
gestureDetector = new GestureDetector(this);
}
public void setImage(Drawable bitmap, Activity activity) {
image = bitmap;
imageSetting(activity);
}
public void setImage(Bitmap bitmap, Activity activity) {
image = new BitmapDrawable(bitmap).getCurrent();
imageSetting(activity);
}
/**
* Works in both landscape and portrait mode.
*/
private void imageSetting(Activity activity) {
scrollX = scrollY = 0;
scalefactor = 0;
imageX = winX = activity.getWindow().getWindowManager()
.getDefaultDisplay().getWidth();
imageY = winY = activity.getWindow().getWindowManager()
.getDefaultDisplay().getHeight();
if (orientation == LANDSCAPE) {
imageX = 3 * imageY / 4;
}
calculatePos();
}
public void calculatePos() {
int tempx, tempy;
tempx = imageX + imageX * scalefactor / 100;
tempy = imageY + imageY * scalefactor / 100;
left = (winX - tempx) / 2;
top = (winY - tempy) / 2;
right = (winX + tempx) / 2;
bottom = (winY + tempy) / 2;
invalidate();
}
/**
* Redraws the bitmap when zoomed or scrolled.
*/
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
if (image == null)
return;
image.setBounds(left + scrollX, top + scrollY, right + scrollX, bottom
+ scrollY);
image.draw(canvas);
}
public void zoomIn() {
scalefactor += SCALING_FACTOR;
calculatePos();
}
public void zoomOut() {
if (scalefactor == 0)
return;
scrollX = scrollY = 0;
scalefactor -= SCALING_FACTOR;
calculatePos();
}
public void scroll(int x, int y) {
scrollX += x / 5;
scrollY += y / 5;
if (scrollX + left > 0) {
scrollX = 0 - left;
} else if (scrollX + right < winX) {
scrollX = winX - right;
}
if (scrollY + top > 0) {
scrollY = 0 - top;
} else if (scrollY + bottom < winY) {
scrollY = winY - bottom;
}
invalidate();
}
@Override
public boolean onTouchEvent(MotionEvent me) {
boolean onTouchEvent = gestureDetector.onTouchEvent(me);
return onTouchEvent;
}
@Override
public boolean onDown(MotionEvent arg0) {
long thisTime = arg0.getEventTime();
if (thisTime - lastTouchTime < 250) {
lastTouchTime = -1;
onDoubleTap();
return true;
}
lastTouchTime = thisTime;
return true;
}
@Override
public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX,
float distanceY) {
if (zoomCtr == 0)
return false;
scroll((int) (e2.getX() - e1.getX()), (int) (e2.getY() - e1.getY()));
return true;
}
private void onDoubleTap() {
if (zoomCtr == 0) {
zoomCtr++;
zoomIn();
return;
}
zoomCtr--;
zoomOut();
}
}
这就是我称之为活动的地方:
And this is where I call the activity:
public class FullScreenPhoto extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_full_screen_photo);
Intent intent = getIntent();
String path = intent.getStringExtra("Path");
ImageView img = (ImageView)findViewById(R.id.photo);
img.setImageURI(Uri.parse(path));
ImageZoomView imageView = new ImageZoomView(
this,getWindow().getWindowManager().getDefaultDisplay().getOrientation());
this.setContentView(imageView);
}
}
它会在屏幕上显示完整图像，但是当点击它时，什么也没有发生.
It display the full image on the screen but when tapping on it, nothing happens.
推荐答案
创建一个名为ZoomFunctionality
ZoomFunctionality
package com.androidhive.work;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Matrix;
import android.graphics.PointF;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.ScaleGestureDetector;
import android.view.View;
import android.widget.ImageView;
public class ZoomFunctionality extends ImageView {
Matrix matrix = new Matrix();
// We can be in one of these 3 states
static final int NONE = 0;
static final int DRAG = 1;
static final int ZOOM = 2;
int mode = NONE;
// Remember some things for zooming
PointF last = new PointF();
PointF start = new PointF();
float minScale = 1f;
float maxScale = 3f;
float[] m;
float redundantXSpace, redundantYSpace;
float width, height;
static final int CLICK = 3;
float saveScale = 1f;
float right, bottom, origWidth, origHeight, bmWidth, bmHeight;
ScaleGestureDetector mScaleDetector;
Context context;
public ZoomFunctionality(Context context) {
super(context);
sharedConstructing(context);
}
public ZoomFunctionality(Context context, AttributeSet attrs) {
super(context, attrs);
sharedConstructing(context);
}
private void sharedConstructing(Context context) {
super.setClickable(true);
this.context = context;
mScaleDetector = new ScaleGestureDetector(context, new ScaleListener());
matrix.setTranslate(1f, 1f);
m = new float[9];
setImageMatrix(matrix);
setScaleType(ScaleType.MATRIX);
setOnTouchListener(new OnTouchListener() {
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);
mode = DRAG;
break;
case MotionEvent.ACTION_MOVE:
if (mode == DRAG) {
float deltaX = curr.x - last.x;
float deltaY = curr.y - last.y;
float scaleWidth = Math.round(origWidth * saveScale);
float scaleHeight = Math.round(origHeight * saveScale);
if (scaleWidth < width) {
deltaX = 0;
if (y + deltaY > 0)
deltaY = -y;
else if (y + deltaY < -bottom)
deltaY = -(y + bottom);
} else if (scaleHeight < height) {
deltaY = 0;
if (x + deltaX > 0)
deltaX = -x;
else if (x + deltaX < -right)
deltaX = -(x + right);
} else {
if (x + deltaX > 0)
deltaX = -x;
else if (x + deltaX < -right)
deltaX = -(x + right);
if (y + deltaY > 0)
deltaY = -y;
else if (y + deltaY < -bottom)
deltaY = -(y + bottom);
}
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; // indicate event was handled
}
});
}
@Override
public void setImageBitmap(Bitmap bm) {
super.setImageBitmap(bm);
if (bm != null) {
bmWidth = bm.getWidth();
bmHeight = bm.getHeight();
}
}
public void setMaxZoom(float x) {
maxScale = x;
}
private class ScaleListener extends
ScaleGestureDetector.SimpleOnScaleGestureListener {
@Override
public boolean onScaleBegin(ScaleGestureDetector detector) {
mode = ZOOM;
return true;
}
@Override
public boolean onScale(ScaleGestureDetector detector) {
float mScaleFactor = detector.getScaleFactor();
float origScale = saveScale;
saveScale *= mScaleFactor;
if (saveScale > maxScale) {
saveScale = maxScale;
mScaleFactor = maxScale / origScale;
} else if (saveScale < minScale) {
saveScale = minScale;
mScaleFactor = minScale / origScale;
}
right = width * saveScale - width
- (2 * redundantXSpace * saveScale);
bottom = height * saveScale - height
- (2 * redundantYSpace * saveScale);
if (origWidth * saveScale <= width
|| origHeight * saveScale <= height) {
matrix.postScale(mScaleFactor, mScaleFactor, width / 2,
height / 2);
if (mScaleFactor < 1) {
matrix.getValues(m);
float x = m[Matrix.MTRANS_X];
float y = m[Matrix.MTRANS_Y];
if (mScaleFactor < 1) {
if (Math.round(origWidth * saveScale) < width) {
if (y < -bottom)
matrix.postTranslate(0, -(y + bottom));
else if (y > 0)
matrix.postTranslate(0, -y);
} else {
if (x < -right)
matrix.postTranslate(-(x + right), 0);
else if (x > 0)
matrix.postTranslate(-x, 0);
}
}
}
} else {
matrix.postScale(mScaleFactor, mScaleFactor,
detector.getFocusX(), detector.getFocusY());
matrix.getValues(m);
float x = m[Matrix.MTRANS_X];
float y = m[Matrix.MTRANS_Y];
if (mScaleFactor < 1) {
if (x < -right)
matrix.postTranslate(-(x + right), 0);
else if (x > 0)
matrix.postTranslate(-x, 0);
if (y < -bottom)
matrix.postTranslate(0, -(y + bottom));
else if (y > 0)
matrix.postTranslate(0, -y);
}
}
return true;
}
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
width = MeasureSpec.getSize(widthMeasureSpec);
height = MeasureSpec.getSize(heightMeasureSpec);
// Fit to screen.
float scale;
float scaleX = (float) width / (float) bmWidth;
float scaleY = (float) height / (float) bmHeight;
scale = Math.min(scaleX, scaleY);
matrix.setScale(scale, scale);
setImageMatrix(matrix);
saveScale = 1f;
// Center the image
redundantYSpace = (float) height - (scale * (float) bmHeight);
redundantXSpace = (float) width - (scale * (float) bmWidth);
redundantYSpace /= (float) 2;
redundantXSpace /= (float) 2;
matrix.postTranslate(redundantXSpace, redundantYSpace);
origWidth = width - 2 * redundantXSpace;
origHeight = height - 2 * redundantYSpace;
right = width * saveScale - width - (2 * redundantXSpace * saveScale);
bottom = height * saveScale - height
- (2 * redundantYSpace * saveScale);
setImageMatrix(matrix);
}
}
现在，只要您想从Activity调用ZoomFunctionality，只需编写以下语句
Now when ever you want to call the ZoomFunctionality from your Activity just write the following statement
BitmapFactory.Options options = new BitmapFactory.Options();
options.inSampleSize = 2;
Bitmap bmp = BitmapFactory.decodeFile(filename, options);
ZoomFunctionality img = new ZoomFunctionality(this);
img.setImageBitmap(bmp);
img.setMaxZoom(4f);
setContentView(img);
注意
bmp:是您要缩放功能的位图图像吗?
this:建议您使用Activity.this
不需要使用BitmapFactoryOptions，但需要从文件名解码
Note
bmp: Is the bitmap image of which you want the zoom functionality
this: Its recommended that you use Activity.this
Its not necessary to use BitmapFactoryOptions but decoding from filename is required
这篇关于Android的图像缩放活动的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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