我是 Android 的新手。我已经关注了这个问题，我成功地缩放了一张图片，这段代码运行良好，有人可以帮我写一下如何在按钮点击时为 zoomin zoomout 编写代码。我不知道如何完成这个任务
这是我关注的教程Tutorial Zoom Image，也关注“Salman's Ayub Answer”
它工作正常，但我未能在放大和缩小图像时应用比例因子
【问题讨论】：
尝试使用PhotoView。我认为它可以满足您的要求。
【讨论】：
您需要将这 2 个方法添加到您的 TouchImageView 类中：
public void zoomIn() {
oldScale = saveScale;
if(saveScale<=maxScale)
{
saveScale += .5;
matrix.setScale(saveScale, saveScale);
setImageMatrix(matrix);
invalidate();
// Center the image
// Center the image
if(bmHeight>bmWidth)
{
redundantXSpace = width - (saveScale * bmWidth);
redundantXSpace /= 2;
}
else
{
redundantYSpace = height - (saveScale * bmHeight) ;
redundantYSpace /= 2;
}
matrix.postTranslate(redundantXSpace , redundantYSpace );
setImageMatrix(matrix);
invalidate();
}
}
public void zoomOut() {
if(saveScale>=minScale)
{
saveScale -= .5;
matrix.setScale(saveScale, saveScale);
setImageMatrix(matrix);
invalidate();
// Center the image
if(bmHeight>bmWidth)
{
redundantXSpace = width - (saveScale * bmWidth);
redundantXSpace /= 2;
}
else
{
redundantYSpace = height - (saveScale * bmHeight) ;
redundantYSpace /= 2;
}
matrix.postTranslate(redundantXSpace , redundantYSpace );
setImageMatrix(matrix);
invalidate();
}
}
这是完整的TouchImageView 类代码，以及这两个方法：
public class TouchImageView extends ImageView {
public 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;
static final int CLICK = 3;
int mode = NONE;
float oldScale = 1.0f;
// Remember some things for zooming
PointF last = new PointF();
PointF start = new PointF();
float minScale = 1f;
float maxScale = 4f;
float[] m;
float redundantXSpace, redundantYSpace;
float width, height;
float saveScale = 1f;
float right, bottom, origWidth, origHeight, bmWidth, bmHeight;
ScaleGestureDetector mScaleDetector;
Context context;
public TouchImageView(Context context) {
super(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() {
@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);
mode = DRAG;
break;
case MotionEvent.ACTION_POINTER_DOWN:
last.set(event.getX(), event.getY());
start.set(last);
mode = ZOOM;
break;
case MotionEvent.ACTION_MOVE:
if (mode == ZOOM || (mode == DRAG && saveScale > minScale)) {
Log.d("******", "ZOOM OR 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);
}else if(mode == DRAG && saveScale == minScale) {
Log.d("******", "DRAG");
}
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);
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)Math.min(Math.max(.95f, detector.getScaleFactor()), 1.05);
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 = width / bmWidth;
float scaleY = height / bmHeight;
scale = Math.min(scaleX, scaleY);
matrix.setScale(scale, scale);
setImageMatrix(matrix);
saveScale = 1f;
// Center the image
redundantYSpace = height - (scale * bmHeight) ;
redundantXSpace = width - (scale * bmWidth);
redundantYSpace /= 2;
redundantXSpace /= 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);
}
public TouchImageView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
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() {
@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);
mode = DRAG;
break;
case MotionEvent.ACTION_POINTER_DOWN:
last.set(event.getX(), event.getY());
start.set(last);
mode = ZOOM;
break;
case MotionEvent.ACTION_MOVE:
if (mode == ZOOM || (mode == DRAG && saveScale > minScale)) {
Log.d("******", "ZOOM OR 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);
}else if(mode == DRAG && saveScale == minScale) {
Log.d("******", "DRAG");
}
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
}
});
}
public TouchImageView(Context context, AttributeSet attrs) {
super(context, attrs);
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() {
@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);
mode = DRAG;
break;
case MotionEvent.ACTION_POINTER_DOWN:
last.set(event.getX(), event.getY());
start.set(last);
mode = ZOOM;
break;
case MotionEvent.ACTION_MOVE:
if (mode == ZOOM || (mode == DRAG && saveScale > minScale)) {
Log.d("******", "ZOOM OR 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);
}else if(mode == DRAG && saveScale == minScale) {
Log.d("******", "DRAG");
}
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
}
});
}
public void zoomIn() {
oldScale = saveScale;
if(saveScale<=maxScale)
{
saveScale += .5;
matrix.setScale(saveScale, saveScale);
setImageMatrix(matrix);
invalidate();
// Center the image
// Center the image
if(bmHeight>bmWidth)
{
redundantXSpace = width - (saveScale * bmWidth);
redundantXSpace /= 2;
}
else
{
redundantYSpace = height - (saveScale * bmHeight) ;
redundantYSpace /= 2;
}
matrix.postTranslate(redundantXSpace , redundantYSpace );
setImageMatrix(matrix);
invalidate();
}
}
public void zoomOut() {
if(saveScale>=minScale)
{
saveScale -= .5;
matrix.setScale(saveScale, saveScale);
setImageMatrix(matrix);
invalidate();
// Center the image
if(bmHeight>bmWidth)
{
redundantXSpace = width - (saveScale * bmWidth);
redundantXSpace /= 2;
}
else
{
redundantYSpace = height - (saveScale * bmHeight) ;
redundantYSpace /= 2;
}
matrix.postTranslate(redundantXSpace , redundantYSpace );
setImageMatrix(matrix);
invalidate();
}
}
}
如何在放大/缩小按钮中使用它们：
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.LAYOUT_NAME);
Button zoonIn = (Button)findViewById(R.id.ZOOM_IN_BUTTON_ID);
Button zoonOut = (Button)findViewById(R.id.ZOOM_OUT_BUTTON_ID);
final TouchImageView touch = (TouchImageView)findViewById(R.id.YOUR_TOUCH_IMAGE_VIEW_)ID);
Bitmap bImage = BitmapFactory.decodeResource(this.getResources(), R.drawable.DRAWABLE_ID);
touch.setImageBitmap(bImage);
touch.setMaxZoom(4f); //change the max level of zoom, default is 3f
zoonIn.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
touch.zoomIn();
}
});
zoonOut.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
touch.zoomOut();
}
});
}
我希望这会有所帮助。
【讨论】：
在按钮上放大/缩小图像最简单的方法是将其显示在 webView 中，然后您可以使用 webView 提供的所有功能。
将图片复制到 assets 文件夹中，然后在 onCreate 中加载：
WebView mWebView = (WebView) findViewById(R.id.webView1);
mWebView.setScrollBarStyle(WebView.SCROLLBARS_OUTSIDE_OVERLAY);
mWebView.setBackgroundColor(Color.parseColor("#ffffff"));
mWebView.loadUrl("file:///android_asset/image.png");
mWebView.getSettings().setBuiltInZoomControls(true);
mWebView.setInitialScale(50);
【讨论】：