Android画布:在图像上绘制透明圆
我正在创建一个像素搜索游戏。因此,我的活动显示了一个ImageView。我想创建一个提示“告诉我对象在哪里”。为此,我需要模糊整个图像,除了围绕对象所在点的圆。我可以显示半透明的黑色背景,而不是模糊。 在画布上绘制半透明矩形没有问题。 但我不知道如何从中裁剪出一个透明的圆。 结果应该如下所示:Android画布:在图像上绘制透明圆,android,image,android-canvas,Android,Image,Android Canvas,我正在创建一个像素搜索游戏。因此,我的活动显示了一个ImageView。我想创建一个提示“告诉我对象在哪里”。为此,我需要模糊整个图像,除了围绕对象所在点的圆。我可以显示半透明的黑色背景,而不是模糊。 在画布上绘制半透明矩形没有问题。 但我不知道如何从中裁剪出一个透明的圆。 结果应该如下所示: 请帮助我在Android SDK上实现相同的结果。所以我最终做到了这一点 首先,我在整个视图上绘制一个半透明的黑色矩形。 之后,使用PorterDuff.Mode.CLEAR我切了一个透明的圆圈来显示猫
请帮助我在Android SDK上实现相同的结果。所以我最终做到了这一点 首先,我在整个视图上绘制一个半透明的黑色矩形。 之后,使用
PorterDuff.Mode.CLEAR
我切了一个透明的圆圈来显示猫的位置
我对PorterDuff.Mode.CLEAR有问题:首先,我得到的是一个黑色的圆圈,而不是一个透明的圆圈
感谢Romain Guy在这里的评论:我知道我的窗口是不透明的,我应该在另一个位图上绘制。只有在视图的画布上绘制之后
以下是我的onDraw
方法:
private Canvas temp;
private Paint paint;
private Paint p = new Paint();
private Paint transparentPaint;
private void init(){
Bitmap bitmap = Bitmap.createBitmap(canvas.getWidth(), canvas.getHeight(), Bitmap.Config.ARGB_8888);
temp = new Canvas(bitmap);
paint = new Paint();
paint.setColor(0xcc000000);
transparentPaint = new Paint();
transparentPaint.setColor(getResources().getColor(android.R.color.transparent));
transparentPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));
}
protected void onDraw(Canvas canvas) {
temp.drawRect(0, 0, temp.getWidth(), temp.getHeight(), paint);
temp.drawCircle(catPosition.x + radius / 2, catPosition.y + radius / 2, radius, transparentPaint);
canvas.drawBitmap(bitmap, 0, 0, p);
}
我没有什么要补充的,但如果有人感兴趣,我将位图分配和所有内容移动到onSizeChanged,这样性能会更好
这里你可以找到一个框架,中间有个“洞”;p>
导入android.content.Context;
导入android.graphics.Bitmap;
导入android.graphics.Canvas;
导入android.graphics.Color;
导入android.graphics.Paint;
导入android.graphics.PorterDuff;
导入android.graphics.PorterDuffXfermode;
导入android.os.Handler;
导入android.util.AttributeSet;
导入android.util.Log;
导入android.widget.FrameLayout;
/**
*由blackvvine于2016年1月1日创建。
*/
公共类FrameLayout扩展了FrameLayout{
私人油漆透明;
私人涂料;
私有位图;
私人帆布临时工;
公共框架布局(上下文){
超级(上下文);
__初始值();
}
公共框架布局(上下文、属性集属性){
超级(上下文,attrs);
__初始值();
}
公共框架布局(上下文上下文、属性集属性、int-defStyleAttr){
super(上下文、attrs、defStyleAttr);
__初始值();
}
私有void\uuuu init\uuuuu(){
透明漆=新漆();
defaultPaint=新绘制();
透明.设置颜色(颜色.透明);
transPaint.setXfermode(新的PorterDuffXfermode(PorterDuff.Mode.CLEAR));
setWillNotDraw(假);
}
@凌驾
已更改尺寸的受保护空心(整数w、整数h、整数oldw、整数oldh){
super.onSizeChanged(w,h,oldw,oldh);
bitmap=bitmap.createBitmap(w,h,bitmap.Config.ARGB_8888);
temp=新画布(位图);
}
@凌驾
受保护的void dispatchDraw(画布){
温度drawColor(颜色透明);
super.dispatchDraw(临时);
临时绘图循环(cx、cy、getWidth()/4、透明);
drawBitmap(位图,0,0,defaultPaint);
if(p<1)
使无效();
其他的
a=假;
}
}
p、 s:虽然它比原始答案效率高很多,但在draw()方法中,它仍然是一项相对繁重的任务,因此,如果您在像我这样的动画中使用此技术,不要期望60.0fps的平滑速度这对我很有效:
canvas.drawCircle(x,y,radius,new Paint(Color.TRANSPARENT))
我通过创建自定义线性布局来实现这一点:
public class CircleDrawActivity extends AppCompatActivity{
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_circle_draw);
}
}
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/rlParent"
android:layout_width="match_parent"
android:layout_height="match_parent">
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="@drawable/lighthouse"
android:scaleType="fitXY" />
<common.customview.CircleOverlayView
android:id="@+id/cicleOverlay"
android:layout_width="match_parent"
android:layout_height="match_parent">
</common.customview.CircleOverlayView>
</RelativeLayout>
<?xml version="1.0" encoding="utf-8"?>
<resources>
<color name="colorPrimary">#3F51B5</color>
<color name="colorPrimaryDark">#303F9F</color>
<color name="colorAccent">#FF4081</color>
</resources>
<resources>
<!-- Default screen margins, per the Android Design guidelines. -->
<dimen name="nav_header_vertical_spacing">16dp</dimen>
<dimen name="nav_header_height">160dp</dimen>
<!-- Default screen margins, per the Android Design guidelines. -->
<dimen name="activity_horizontal_margin">16dp</dimen>
<dimen name="activity_vertical_margin">16dp</dimen>
<dimen name="fab_margin">16dp</dimen>
<dimen name="radius">50dp</dimen>
</resources>
检查屏幕截图:
public class CircleDrawActivity extends AppCompatActivity{
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_circle_draw);
}
}
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/rlParent"
android:layout_width="match_parent"
android:layout_height="match_parent">
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="@drawable/lighthouse"
android:scaleType="fitXY" />
<common.customview.CircleOverlayView
android:id="@+id/cicleOverlay"
android:layout_width="match_parent"
android:layout_height="match_parent">
</common.customview.CircleOverlayView>
</RelativeLayout>
<?xml version="1.0" encoding="utf-8"?>
<resources>
<color name="colorPrimary">#3F51B5</color>
<color name="colorPrimaryDark">#303F9F</color>
<color name="colorAccent">#FF4081</color>
</resources>
<resources>
<!-- Default screen margins, per the Android Design guidelines. -->
<dimen name="nav_header_vertical_spacing">16dp</dimen>
<dimen name="nav_header_height">160dp</dimen>
<!-- Default screen margins, per the Android Design guidelines. -->
<dimen name="activity_horizontal_margin">16dp</dimen>
<dimen name="activity_vertical_margin">16dp</dimen>
<dimen name="fab_margin">16dp</dimen>
<dimen name="radius">50dp</dimen>
</resources>
CircleOverlayView.java
import android.annotation.TargetApi;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.PorterDuff;
import android.graphics.PorterDuffXfermode;
import android.graphics.RectF;
import android.os.Build;
import android.util.AttributeSet;
import android.widget.LinearLayout;
/**
* Created by hiren on 10/01/16.
*/
public class CircleOverlayView extends LinearLayout {
private Bitmap bitmap;
public CircleOverlayView(Context context) {
super(context);
}
public CircleOverlayView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public CircleOverlayView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
@TargetApi(Build.VERSION_CODES.LOLLIPOP)
public CircleOverlayView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
super(context, attrs, defStyleAttr, defStyleRes);
}
@Override
protected void dispatchDraw(Canvas canvas) {
super.dispatchDraw(canvas);
if (bitmap == null) {
createWindowFrame();
}
canvas.drawBitmap(bitmap, 0, 0, null);
}
protected void createWindowFrame() {
bitmap = Bitmap.createBitmap(getWidth(), getHeight(), Bitmap.Config.ARGB_8888);
Canvas osCanvas = new Canvas(bitmap);
RectF outerRectangle = new RectF(0, 0, getWidth(), getHeight());
Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
paint.setColor(getResources().getColor(R.color.colorPrimary));
paint.setAlpha(99);
osCanvas.drawRect(outerRectangle, paint);
paint.setColor(Color.TRANSPARENT);
paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_OUT));
float centerX = getWidth() / 2;
float centerY = getHeight() / 2;
float radius = getResources().getDimensionPixelSize(R.dimen.radius);
osCanvas.drawCircle(centerX, centerY, radius, paint);
}
@Override
public boolean isInEditMode() {
return true;
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
super.onLayout(changed, l, t, r, b);
bitmap = null;
}
}
CircleDrawActivity.java:
public class CircleDrawActivity extends AppCompatActivity{
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_circle_draw);
}
}
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/rlParent"
android:layout_width="match_parent"
android:layout_height="match_parent">
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="@drawable/lighthouse"
android:scaleType="fitXY" />
<common.customview.CircleOverlayView
android:id="@+id/cicleOverlay"
android:layout_width="match_parent"
android:layout_height="match_parent">
</common.customview.CircleOverlayView>
</RelativeLayout>
<?xml version="1.0" encoding="utf-8"?>
<resources>
<color name="colorPrimary">#3F51B5</color>
<color name="colorPrimaryDark">#303F9F</color>
<color name="colorAccent">#FF4081</color>
</resources>
<resources>
<!-- Default screen margins, per the Android Design guidelines. -->
<dimen name="nav_header_vertical_spacing">16dp</dimen>
<dimen name="nav_header_height">160dp</dimen>
<!-- Default screen margins, per the Android Design guidelines. -->
<dimen name="activity_horizontal_margin">16dp</dimen>
<dimen name="activity_vertical_margin">16dp</dimen>
<dimen name="fab_margin">16dp</dimen>
<dimen name="radius">50dp</dimen>
</resources>
活动\u圈\u画.xml:
public class CircleDrawActivity extends AppCompatActivity{
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_circle_draw);
}
}
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/rlParent"
android:layout_width="match_parent"
android:layout_height="match_parent">
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="@drawable/lighthouse"
android:scaleType="fitXY" />
<common.customview.CircleOverlayView
android:id="@+id/cicleOverlay"
android:layout_width="match_parent"
android:layout_height="match_parent">
</common.customview.CircleOverlayView>
</RelativeLayout>
<?xml version="1.0" encoding="utf-8"?>
<resources>
<color name="colorPrimary">#3F51B5</color>
<color name="colorPrimaryDark">#303F9F</color>
<color name="colorAccent">#FF4081</color>
</resources>
<resources>
<!-- Default screen margins, per the Android Design guidelines. -->
<dimen name="nav_header_vertical_spacing">16dp</dimen>
<dimen name="nav_header_height">160dp</dimen>
<!-- Default screen margins, per the Android Design guidelines. -->
<dimen name="activity_horizontal_margin">16dp</dimen>
<dimen name="activity_vertical_margin">16dp</dimen>
<dimen name="fab_margin">16dp</dimen>
<dimen name="radius">50dp</dimen>
</resources>
colors.xml:
public class CircleDrawActivity extends AppCompatActivity{
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_circle_draw);
}
}
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/rlParent"
android:layout_width="match_parent"
android:layout_height="match_parent">
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="@drawable/lighthouse"
android:scaleType="fitXY" />
<common.customview.CircleOverlayView
android:id="@+id/cicleOverlay"
android:layout_width="match_parent"
android:layout_height="match_parent">
</common.customview.CircleOverlayView>
</RelativeLayout>
<?xml version="1.0" encoding="utf-8"?>
<resources>
<color name="colorPrimary">#3F51B5</color>
<color name="colorPrimaryDark">#303F9F</color>
<color name="colorAccent">#FF4081</color>
</resources>
<resources>
<!-- Default screen margins, per the Android Design guidelines. -->
<dimen name="nav_header_vertical_spacing">16dp</dimen>
<dimen name="nav_header_height">160dp</dimen>
<!-- Default screen margins, per the Android Design guidelines. -->
<dimen name="activity_horizontal_margin">16dp</dimen>
<dimen name="activity_vertical_margin">16dp</dimen>
<dimen name="fab_margin">16dp</dimen>
<dimen name="radius">50dp</dimen>
</resources>
#3F51B5
#303F9F
#FF4081
dimens.xml:
public class CircleDrawActivity extends AppCompatActivity{
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_circle_draw);
}
}
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/rlParent"
android:layout_width="match_parent"
android:layout_height="match_parent">
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="@drawable/lighthouse"
android:scaleType="fitXY" />
<common.customview.CircleOverlayView
android:id="@+id/cicleOverlay"
android:layout_width="match_parent"
android:layout_height="match_parent">
</common.customview.CircleOverlayView>
</RelativeLayout>
<?xml version="1.0" encoding="utf-8"?>
<resources>
<color name="colorPrimary">#3F51B5</color>
<color name="colorPrimaryDark">#303F9F</color>
<color name="colorAccent">#FF4081</color>
</resources>
<resources>
<!-- Default screen margins, per the Android Design guidelines. -->
<dimen name="nav_header_vertical_spacing">16dp</dimen>
<dimen name="nav_header_height">160dp</dimen>
<!-- Default screen margins, per the Android Design guidelines. -->
<dimen name="activity_horizontal_margin">16dp</dimen>
<dimen name="activity_vertical_margin">16dp</dimen>
<dimen name="fab_margin">16dp</dimen>
<dimen name="radius">50dp</dimen>
</resources>
16dp
160dp
16dp
16dp
16dp
50dp
希望这能对你有所帮助。@Robert的回答实际上向我展示了如何解决这个问题,但他的代码不起作用。因此,我更新了他的解决方案并使其生效:
public class CaptureLayerView extends View {
private Bitmap bitmap;
private Canvas cnvs;
private Paint p = new Paint();
private Paint transparentPaint = new Paint();;
private Paint semiTransparentPaint = new Paint();;
private int parentWidth;
private int parentHeight;
private int radius = 100;
public CaptureLayerView(Context context) {
super(context);
init();
}
public CaptureLayerView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
private void init() {
transparentPaint.setColor(getResources().getColor(android.R.color.transparent));
transparentPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));
semiTransparentPaint.setColor(getResources().getColor(R.color.colorAccent));
semiTransparentPaint.setAlpha(70);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
bitmap = Bitmap.createBitmap(parentWidth, parentHeight, Bitmap.Config.ARGB_8888);
cnvs = new Canvas(bitmap);
cnvs.drawRect(0, 0, cnvs.getWidth(), cnvs.getHeight(), semiTransparentPaint);
cnvs.drawCircle(parentWidth / 2, parentHeight / 2, radius, transparentPaint);
canvas.drawBitmap(bitmap, 0, 0, p);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
parentWidth = MeasureSpec.getSize(widthMeasureSpec);
parentHeight = MeasureSpec.getSize(heightMeasureSpec);
this.setMeasuredDimension(parentWidth, parentHeight);
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
}
现在,在如下任何布局中使用此视图:
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent">
<SurfaceView
android:id="@+id/surfaceView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center">
</SurfaceView>
<com.example.myapp.CaptureLayerView
android:layout_width="match_parent"
android:layout_height="match_parent" />
<Button
android:id="@+id/btnTakePicture"
android:layout_width="match_parent"
android:layout_height="80dp"
android:onClick="onClickPicture"
android:text="@string/take_picture">
</Button>
这里我想要在SurfaceView上有一个半透明层,中间有一个透明的圆圈。
P.S.这段代码不是优化的,因为它在onDraw方法中创建位图,这是因为我无法在init方法中获得父视图的宽度和高度,所以我只能在onDraw中知道它们。我找到了一个没有位图绘制和创建的解决方案。以下是我实施的结果:
您需要使用Clear
paint创建自定义的FrameLayout
和drawCircle
:
mBackgroundPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));
另外,不要忘记禁用硬件加速并调用setWillNotDraw(false)
,因为我们将覆盖onDraw
方法
setWillNotDraw(false);
setLayerType(LAYER_TYPE_HARDWARE, null);
完整示例如下:
public class TutorialView extends FrameLayout {
private static final float RADIUS = 200;
private Paint mBackgroundPaint;
private float mCx = -1;
private float mCy = -1;
private int mTutorialColor = Color.parseColor("#D20E0F02");
public TutorialView(Context context) {
super(context);
init();
}
public TutorialView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public TutorialView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init();
}
@TargetApi(Build.VERSION_CODES.LOLLIPOP)
public TutorialView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
super(context, attrs, defStyleAttr, defStyleRes);
init();
}
private void init() {
setWillNotDraw(false);
setLayerType(LAYER_TYPE_HARDWARE, null);
mBackgroundPaint = new Paint();
mBackgroundPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));
}
@Override
public boolean onTouchEvent(MotionEvent event) {
mCx = event.getX();
mCy = event.getY();
invalidate();
return true;
}
@Override
protected void onDraw(Canvas canvas) {
canvas.drawColor(mTutorialColor);
if (mCx >= 0 && mCy >= 0) {
canvas.drawCircle(mCx, mCy, RADIUS, mBackgroundPaint);
}
}
}
PS:这个实现只是在自身内部绘制了一个洞,您需要在布局中放置背景,并在顶部添加这个TutorialView
。如果您在使用不透明背景的视图上获取透明圆形剪切图时遇到困难。为了让它工作,我将自定义布局视图设置为具有XML透明背景,然后使用线条绘制布局所需的背景色
cv.drawColor(Color.BLUE); //replace with your desired background color
我上面链接的答案中的完整OnDraw方法:
@Override
protected void onDraw(Canvas canvas) {
int w = getWidth();
int h = getHeight();
int radius = w > h ? h / 2 : w / 2;
bm.eraseColor(Color.TRANSPARENT);
cv.drawColor(Color.BLUE);
cv.drawCircle(w / 2, h / 2, radius, eraser);
canvas.drawBitmap(bm, 0, 0, null);
super.onDraw(canvas);
}
公共类CircleBlur扩展活动实现View.OnTouchListener{
SeekBar-SeekBar;
ImageView图像,image1;
私人油漆;
位图圆,模糊;
私有矩阵=新矩阵();
私有矩阵savedMatrix=新矩阵();
私有静态final int NONE=0;
专用静态最终整数拖动=1;
私有静态最终整数缩放=2;
私有int模式=无;
private PointF start=new PointF();
私有点f mid=新点f();
私有浮动oldDist=1f;
浮动newRot=0f;
专用浮点数d=0f;
私有浮点[]lastEvent=null;
脉波重复间隔