Android 如何使用最小值和最大值放大布局
我有以下功能,可以无限放大和缩小,但是我正在尝试为缩放设置Android 如何使用最小值和最大值放大布局,android,pinchzoom,Android,Pinchzoom,我有以下功能,可以无限放大和缩小,但是我正在尝试为缩放设置min和max值,以便布局不会太大或太小。我已经尝试过使用,但我不明白在代码中应该放在哪里 private static final float MIN_ZOOM = 1.0f; private static final float MAX_ZOOM = //set Maximum zooming level float scale = Math.max(MIN_ZOOM, Math.min(scale, MAX_ZOOM)); pub
min
和max
值,以便布局不会太大或太小。我已经尝试过使用,但我不明白在代码中应该放在哪里
private static final float MIN_ZOOM = 1.0f;
private static final float MAX_ZOOM = //set Maximum zooming level
float scale = Math.max(MIN_ZOOM, Math.min(scale, MAX_ZOOM));
public class ZoomableView extends RelativeLayout {
// States.
private static final byte NONE = 0;
private static final byte DRAG = 1;
private static final byte ZOOM = 2;
private byte mode = NONE;
// Matrices used to move and zoom image.
private Matrix matrix = new Matrix();
private Matrix matrixInverse = new Matrix();
private Matrix savedMatrix = new Matrix();
// Parameters for zooming.
private PointF start = new PointF();
private PointF mid = new PointF();
private float oldDist = 1f;
private float[] lastEvent = null;
private long lastDownTime = 0l;
private float[] mDispatchTouchEventWorkingArray = new float[2];
private float[] mOnTouchEventWorkingArray = new float[2];
@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
mDispatchTouchEventWorkingArray[0] = ev.getX();
mDispatchTouchEventWorkingArray[1] = ev.getY();
mDispatchTouchEventWorkingArray = screenPointsToScaledPoints(mDispatchTouchEventWorkingArray);
ev.setLocation(mDispatchTouchEventWorkingArray[0], mDispatchTouchEventWorkingArray[1]);
return super.dispatchTouchEvent(ev);
}
public ZoomableView(Context context) {
super(context);
init(context);
}
public ZoomableView(Context context, AttributeSet attrs) {
super(context, attrs);
init(context);
}
public ZoomableView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init(context);
}
private void init(Context context) {
}
/**
* Determine the space between the first two fingers
*/
private float spacing(MotionEvent event) {
float x = event.getX(0) - event.getX(1);
float y = event.getY(0) - event.getY(1);
return (float) Math.sqrt(x * x + y * y);
}
/**
* Calculate the mid point of the first two fingers
*/
private void midPoint(PointF point, MotionEvent event) {
float x = event.getX(0) + event.getX(1);
float y = event.getY(0) + event.getY(1);
point.set(x / 2, y / 2);
}
private float[] scaledPointsToScreenPoints(float[] a) {
matrix.mapPoints(a);
return a;
}
private float[] screenPointsToScaledPoints(float[] a) {
matrixInverse.mapPoints(a);
return a;
}
@Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
int childCount = getChildCount();
for (int i = 0; i < childCount; i++) {
View child = getChildAt(i);
if (child.getVisibility() != GONE) {
child.layout(left, top, left + child.getMeasuredWidth(), top + child.getMeasuredHeight());
}
}
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int childCount = getChildCount();
for (int i = 0; i < childCount; i++) {
View child = getChildAt(i);
if (child.getVisibility() != GONE) {
measureChild(child, widthMeasureSpec, heightMeasureSpec);
}
}
}
@Override
protected void dispatchDraw(Canvas canvas) {
float[] values = new float[9];
matrix.getValues(values);
canvas.save();
canvas.translate(values[Matrix.MTRANS_X], values[Matrix.MTRANS_Y]);
canvas.scale(values[Matrix.MSCALE_X], values[Matrix.MSCALE_Y]);
super.dispatchDraw(canvas);
canvas.restore();
}
@Override
public boolean onTouchEvent(MotionEvent event) {
// handle touch events here
mOnTouchEventWorkingArray[0] = event.getX();
mOnTouchEventWorkingArray[1] = event.getY();
mOnTouchEventWorkingArray = scaledPointsToScreenPoints(mOnTouchEventWorkingArray);
event.setLocation(mOnTouchEventWorkingArray[0], mOnTouchEventWorkingArray[1]);
switch (event.getAction() & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN:
savedMatrix.set(matrix);
mode = DRAG;
lastEvent = null;
long downTime = event.getDownTime();
if (downTime - lastDownTime < 300l) {
float density = getResources().getDisplayMetrics().density;
if (Math.max(Math.abs(start.x - event.getX()), Math.abs(start.y - event.getY())) < 40.f * density) {
savedMatrix.set(matrix);
mid.set(event.getX(), event.getY());
mode = ZOOM;
lastEvent = new float[4];
lastEvent[0] = lastEvent[1] = event.getX();
lastEvent[2] = lastEvent[3] = event.getY();
}
lastDownTime = 0l;
} else {
lastDownTime = downTime;
}
start.set(event.getX(), event.getY());
break;
case MotionEvent.ACTION_POINTER_DOWN:
oldDist = spacing(event);
if (oldDist > 10f) {
savedMatrix.set(matrix);
midPoint(mid, event);
mode = ZOOM;
}
lastEvent = new float[4];
lastEvent[0] = event.getX(0);
lastEvent[1] = event.getX(1);
lastEvent[2] = event.getY(0);
lastEvent[3] = event.getY(1);
break;
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_POINTER_UP:
mode = NONE;
lastEvent = null;
break;
case MotionEvent.ACTION_MOVE:
final float density = getResources().getDisplayMetrics().density;
if (mode == DRAG) {
matrix.set(savedMatrix);
float dx = event.getX() - start.x;
float dy = event.getY() - start.y;
matrix.postTranslate(dx, dy);
matrix.invert(matrixInverse);
if (Math.max(Math.abs(start.x - event.getX()), Math.abs(start.y - event.getY())) > 20.f * density) {
lastDownTime = 0l;
}
} else if (mode == ZOOM) {
if (event.getPointerCount() > 1) {
float newDist = spacing(event);
if (newDist > 10f * density) {
matrix.set(savedMatrix);
float scale = (newDist / oldDist);
matrix.postScale(scale, scale, mid.x, mid.y);
matrix.invert(matrixInverse);
}
} else {
matrix.set(savedMatrix);
float scale = event.getY() / start.y;
matrix.postScale(scale, scale, mid.x, mid.y);
matrix.invert(matrixInverse);
}
}
break;
}
invalidate();
return true;
}
}
private static final float MIN_ZOOM=1.0f;
私有静态最终浮点最大值\u缩放=//设置最大缩放级别
浮动比例=数学最大值(最小缩放,数学最小值(缩放,最大缩放));
公共类ZoomableView扩展了RelativeLayout{
//国家。
私有静态最终字节NONE=0;
私有静态最终字节拖拽=1;
私有静态最终字节缩放=2;
专用字节模式=无;
//用于移动和缩放图像的矩阵。
私有矩阵=新矩阵();
私有矩阵matrixInverse=新矩阵();
私有矩阵savedMatrix=新矩阵();
//用于缩放的参数。
private PointF start=new PointF();
私有点f mid=新点f();
私有浮动oldDist=1f;
私有浮点[]lastEvent=null;
私人长时间停机时间=0l;
私有浮动[]mDispatchTouchEventWorkingArray=新浮动[2];
私有浮动[]mOnTouchEventWorkingArray=新浮动[2];
@凌驾
公共布尔dispatchTouchEvent(MotionEvent ev){
mDispatchTouchEventWorkingArray[0]=ev.getX();
mDispatchTouchEventWorkingArray[1]=ev.getY();
mDispatchTouchEventWorkingArray=屏幕点到缩放点(mDispatchTouchEventWorkingArray);
ev.setLocation(mDispatchTouchEventWorkingArray[0],mDispatchTouchEventWorkingArray[1]);
返回超级dispatchTouchEvent(ev);
}
公共缩放视图(上下文){
超级(上下文);
init(上下文);
}
公共ZoomableView(上下文、属性集属性){
超级(上下文,attrs);
init(上下文);
}
公共ZoomableView(上下文、属性集属性、int defStyleAttr){
super(上下文、attrs、defStyleAttr);
init(上下文);
}
私有void init(上下文){
}
/**
*确定前两个手指之间的间距
*/
专用浮动间距(MotionEvent事件){
float x=event.getX(0)-event.getX(1);
float y=event.getY(0)-event.getY(1);
返回(浮点)数学sqrt(x*x+y*y);
}
/**
*计算前两个手指的中点
*/
专用空心中点(点F点、MotionEvent事件){
float x=event.getX(0)+event.getX(1);
float y=event.getY(0)+event.getY(1);
点集(x/2,y/2);
}
专用浮点[]缩放点到屏幕点(浮点[]a){
矩阵.地图点(a);
返回a;
}
专用浮点[]屏幕点缩放点(浮点[]a){
matrixInverse.地图点(a);
返回a;
}
@凌驾
仅限受保护的空心布局(布尔值已更改、整数左侧、整数顶部、整数右侧、整数底部){
int childCount=getChildCount();
for(int i=0;i10f){
savedMatrix.set(矩阵);
中点(中点,事件);
模式=缩放;
}
lastEvent=新浮点[4];
lastEvent[0]=event.getX(0);
lastEvent[1]=event.getX(1);
public class ZoomableView extends RelativeLayout {
@Override
public int getMaxZoomLevel() {
return 22;
}
@Override
public int getMinZoomLevel() {
return 12;
}
}