在我的应用程序中，我有一个带有粒子爆炸动画的表面 View 。我试图使该表面 View 透明。透明化后，爆炸动画有问题。我附上了原始动画的屏幕截图以及使表面 View 透明后的屏幕截图。当设置背景颜色为黑色时，它工作正常。
主 Activity .java
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
LinearLayout surface = (LinearLayout)findViewById(R.id.middleSurface);
surface.addView(new MainGamePanel(this));
}
}
主游戏面板.java
public class MainGamePanel extends SurfaceView implements
SurfaceHolder.Callback {
private static final String TAG = MainGamePanel.class.getSimpleName();
private static final int EXPLOSION_SIZE = 200;
private MainThread thread;
private Explosion explosion;
// the fps to be displayed
private String avgFps;
public void setAvgFps(String avgFps) {
this.avgFps = avgFps;
}
public MainGamePanel(Context context) {
super(context);
// adding the callback (this) to the surface holder to intercept events
this.setBackgroundColor(Color.TRANSPARENT); //To make canvas transparent
this.setZOrderOnTop(true); //To make canvas transparent
getHolder().setFormat(PixelFormat.TRANSPARENT); //To make canvas transparent!
getHolder().addCallback(this);
// make the GamePanel focusable so it can handle events
setFocusable(true);
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
// create the game loop thread
thread = new MainThread(getHolder(), this);
// at this point the surface is created and
// we can safely start the game loop
thread.setRunning(true);
thread.start();
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
Log.d(TAG, "Surface is being destroyed");
// tell the thread to shut down and wait for it to finish
// this is a clean shutdown
boolean retry = true;
while (retry) {
try {
thread.setRunning(false);
thread.join();
retry = false;
} catch (InterruptedException e) {
// try again shutting down the thread
}
}
Log.d(TAG, "Thread was shut down cleanly");
}
@Override
public boolean onTouchEvent(MotionEvent event) {
if (event.getAction() == MotionEvent.ACTION_DOWN) {
// handle touch
// check if explosion is null or if it is still active
if (explosion == null || explosion.getState() == Explosion.STATE_DEAD) {
explosion = new Explosion(EXPLOSION_SIZE, (int)event.getX(), (int)event.getY());
}
}
return true;
}
public void render(Canvas canvas) {
canvas.drawColor(Color.argb(0, 0, 0, 0)); //To make canvas transparent
// render explosions
if (explosion != null) {
explosion.draw(canvas);
}
// display fps
//displayFps(canvas, avgFps);
// display border
/*Paint paint = new Paint();
paint.setColor(Color.GREEN);
canvas.drawLines(new float[]{
0,0, canvas.getWidth()-1,0,
canvas.getWidth()-1,0, canvas.getWidth()-1,canvas.getHeight()-1,
canvas.getWidth()-1,canvas.getHeight()-1, 0,canvas.getHeight()-1,
0,canvas.getHeight()-1, 0,0
}, paint);*/
}
/**
* This is the game update method. It iterates through all the objects
* and calls their update method if they have one or calls specific
* engine's update method.
*/
public void update() {
// update explosions
if (explosion != null && explosion.isAlive()) {
explosion.update(getHolder().getSurfaceFrame());
}
}
private void displayFps(Canvas canvas, String fps) {
if (canvas != null && fps != null) {
Paint paint = new Paint();
paint.setARGB(255, 255, 255, 255);
canvas.drawText(fps, this.getWidth() - 50, 20, paint);
}
}
}
爆炸.java
public class Explosion {
private static final String TAG = Explosion.class.getSimpleName();
public static final int STATE_ALIVE = 0; // at least 1 particle is alive
public static final int STATE_DEAD = 1; // all particles are dead
private Particle[] particles; // particles in the explosion
private int x, y; // the explosion's origin
private float gravity; // the gravity of the explosion (+ upward, - down)
private float wind; // speed of wind on horizontal
private int size; // number of particles
private int state; // whether it's still active or not
public Explosion(int particleNr, int x, int y) {
Log.d(TAG, "Explosion created at " + x + "," + y);
this.state = STATE_ALIVE;
this.particles = new Particle[particleNr];
for (int i = 0; i < this.particles.length; i++) {
Particle p = new Particle(x, y);
this.particles[i] = p;
}
this.size = particleNr;
}
public Particle[] getParticles() {
return particles;
}
public void setParticles(Particle[] particles) {
this.particles = particles;
}
public int getX() {
return x;
}
public void setX(int x) {
this.x = x;
}
public int getY() {
return y;
}
public void setY(int y) {
this.y = y;
}
public float getGravity() {
return gravity;
}
public void setGravity(float gravity) {
this.gravity = gravity;
}
public float getWind() {
return wind;
}
public void setWind(float wind) {
this.wind = wind;
}
public int getSize() {
return size;
}
public void setSize(int size) {
this.size = size;
}
public int getState() {
return state;
}
public void setState(int state) {
this.state = state;
}
// helper methods -------------------------
public boolean isAlive() {
return this.state == STATE_ALIVE;
}
public boolean isDead() {
return this.state == STATE_DEAD;
}
public void update() {
if (this.state != STATE_DEAD) {
boolean isDead = true;
for (int i = 0; i < this.particles.length; i++) {
if (this.particles[i].isAlive()) {
this.particles[i].update();
isDead = false;
}
}
if (isDead)
this.state = STATE_DEAD;
}
}
public void update(Rect container) {
if (this.state != STATE_DEAD) {
boolean isDead = true;
for (int i = 0; i < this.particles.length; i++) {
if (this.particles[i].isAlive()) {
this.particles[i].update(container);
// this.particles[i].update();
isDead = false;
}
}
if (isDead)
this.state = STATE_DEAD;
}
}
public void draw(Canvas canvas) {
for(int i = 0; i < this.particles.length; i++) {
if (this.particles[i].isAlive()) {
this.particles[i].draw(canvas);
}
}
}
}
粒子.java
public class Particle {
public static final int STATE_ALIVE = 0; // particle is alive
public static final int STATE_DEAD = 1; // particle is dead
public static final int DEFAULT_LIFETIME = 200; // play with this
public static final int MAX_DIMENSION = 5; // the maximum width or height
public static final int MAX_SPEED = 10; // maximum speed (per update)
private int state; // particle is alive or dead
private float widht; // width of the particle
private float height; // height of the particle
private float x, y; // horizontal and vertical position
private double xv, yv; // vertical and horizontal velocity
private int age; // current age of the particle
private int lifetime; // particle dies when it reaches this value
private int color; // the color of the particle
private Paint paint; // internal use to avoid instantiation
public int getState() {
return state;
}
public void setState(int state) {
this.state = state;
}
public float getWidht() {
return widht;
}
public void setWidht(float widht) {
this.widht = widht;
}
public float getHeight() {
return height;
}
public void setHeight(float height) {
this.height = height;
}
public float getX() {
return x;
}
public void setX(float x) {
this.x = x;
}
public float getY() {
return y;
}
public void setY(float y) {
this.y = y;
}
public double getXv() {
return xv;
}
public void setXv(double xv) {
this.xv = xv;
}
public double getYv() {
return yv;
}
public void setYv(double yv) {
this.yv = yv;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public int getLifetime() {
return lifetime;
}
public void setLifetime(int lifetime) {
this.lifetime = lifetime;
}
public int getColor() {
return color;
}
public void setColor(int color) {
this.color = color;
}
// helper methods -------------------------
public boolean isAlive() {
return this.state == STATE_ALIVE;
}
public boolean isDead() {
return this.state == STATE_DEAD;
}
public Particle(int x, int y) {
this.x = x;
this.y = y;
this.state = Particle.STATE_ALIVE;
this.widht = rndInt(1, MAX_DIMENSION);
this.height = this.widht;
// this.height = rnd(1, MAX_DIMENSION);
this.lifetime = DEFAULT_LIFETIME;
this.age = 0;
this.xv = (rndDbl(0, MAX_SPEED * 2) - MAX_SPEED);
this.yv = (rndDbl(0, MAX_SPEED * 2) - MAX_SPEED);
// smoothing out the diagonal speed
if (xv * xv + yv * yv > MAX_SPEED * MAX_SPEED) {
xv *= 0.7;
yv *= 0.7;
}
this.color = Color.argb(255, rndInt(0, 255), rndInt(0, 255), rndInt(0, 255));
this.paint = new Paint(this.color);
}
/**
* Resets the particle
* @param x
* @param y
*/
public void reset(float x, float y) {
this.state = Particle.STATE_ALIVE;
this.x = x;
this.y = y;
this.age = 0;
}
// Return an integer that ranges from min inclusive to max inclusive.
static int rndInt(int min, int max) {
return (int) (min + Math.random() * (max - min + 1));
}
static double rndDbl(double min, double max) {
return min + (max - min) * Math.random();
}
public void update() {
if (this.state != STATE_DEAD) {
this.x += this.xv;
this.y += this.yv;
// extract alpha
int a = this.color >>> 24;
a -= 2; // fade by 5
if (a <= 0) { // if reached transparency kill the particle
this.state = STATE_DEAD;
} else {
this.color = (this.color & 0x00ffffff) + (a << 24); // set the new alpha
this.paint.setAlpha(a);
this.age++; // increase the age of the particle
// this.widht *= 1.05;
// this.height *= 1.05;
}
if (this.age >= this.lifetime) { // reached the end if its life
this.state = STATE_DEAD;
}
// http://lab.polygonal.de/2007/05/10/bitwise-gems-fast-integer-math/
//32bit
// var color:uint = 0xff336699;
// var a:uint = color >>> 24;
// var r:uint = color >>> 16 & 0xFF;
// var g:uint = color >>> 8 & 0xFF;
// var b:uint = color & 0xFF;
}
}
public void update(Rect container) {
// update with collision
if (this.isAlive()) {
if (this.x <= container.left || this.x >= container.right - this.widht) {
this.xv *= -1;
}
// Bottom is 480 and top is 0 !!!
if (this.y <= container.top || this.y >= container.bottom - this.height) {
this.yv *= -1;
}
}
update();
}
public void draw(Canvas canvas) {
// paint.setARGB(255, 128, 255, 50);
paint.setColor(this.color);
canvas.drawRect(this.x, this.y, this.x + this.widht, this.y + this.height, paint);
// canvas.drawCircle(x, y, widht, paint);
}
}
activity_main.xml
<RelativeLayout 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"
android:background="#556168"
tools:context="com.offero.MainActivity$PlaceholderFragment" >
<ImageView
android:id="@+id/imageView4"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:scaleType="centerCrop"
android:src="@drawable/bg" />
<ImageView
android:id="@+id/imageView2"
android:layout_width="70dp"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_alignParentRight="true"
android:layout_marginRight="5dp"
android:src="@drawable/cloud2" />
<ImageView
android:id="@+id/imageView1"
android:layout_width="70dp"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_alignParentLeft="true"
android:layout_marginLeft="5dp"
android:src="@drawable/cloud1" />
<ImageView
android:id="@+id/ImageView02"
android:layout_width="70dp"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/imageView2"
android:layout_alignParentBottom="true"
android:layout_marginRight="5dp"
android:src="@drawable/cloud2" />
<ImageView
android:id="@+id/ImageView01"
android:layout_width="70dp"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/imageView1"
android:layout_alignParentBottom="true"
android:layout_marginLeft="5dp"
android:src="@drawable/cloud1" />
<ImageView
android:id="@+id/ImageView03"
android:layout_width="70dp"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:src="@drawable/cloud1" />
<ImageView
android:id="@+id/imageView3"
android:layout_width="wrap_content"
android:layout_height="150dp"
android:layout_centerInParent="true"
android:src="@drawable/rocket" />
<ImageView
android:id="@+id/imageView5"
android:layout_width="wrap_content"
android:layout_height="58dp"
android:layout_alignTop="@+id/imageView3"
android:layout_centerHorizontal="true"
android:src="@drawable/rocketpeice2" />
<ImageView
android:id="@+id/imageView6"
android:layout_width="wrap_content"
android:layout_height="60dp"
android:layout_below="@+id/imageView5"
android:layout_centerHorizontal="true"
android:src="@drawable/rocketpeice1" />
<ImageView
android:id="@+id/imageView_star1"
android:layout_width="wrap_content"
android:layout_height="10dp"
android:layout_alignTop="@+id/imageView6"
android:layout_centerHorizontal="true"
android:src="@drawable/star" />
<ImageView
android:id="@+id/imageView_star2"
android:layout_width="wrap_content"
android:layout_height="15dp"
android:layout_alignTop="@+id/imageView6"
android:layout_centerHorizontal="true"
android:src="@drawable/star" />
<ImageView
android:id="@+id/ImageView_star3"
android:layout_width="wrap_content"
android:layout_height="7dp"
android:layout_alignTop="@+id/imageView6"
android:layout_centerHorizontal="true"
android:src="@drawable/star" />
<ImageView
android:id="@+id/ImageView_star4"
android:layout_width="wrap_content"
android:layout_height="12dp"
android:layout_alignBottom="@+id/ImageView_star3"
android:layout_centerHorizontal="true"
android:src="@drawable/star" />
<ImageView
android:id="@+id/ImageView_star5"
android:layout_width="wrap_content"
android:layout_height="10dp"
android:layout_alignLeft="@+id/imageView_star1"
android:layout_below="@+id/imageView5"
android:src="@drawable/star" />
<ImageView
android:id="@+id/ImageView_star6"
android:layout_width="wrap_content"
android:layout_height="15dp"
android:layout_alignLeft="@+id/imageView_star1"
android:layout_alignTop="@+id/imageView6"
android:src="@drawable/star" />
<ImageView
android:id="@+id/ImageView_star7"
android:layout_width="wrap_content"
android:layout_height="7dp"
android:layout_alignLeft="@+id/imageView_star1"
android:layout_below="@+id/ImageView_star3"
android:src="@drawable/star" />
<ImageView
android:id="@+id/ImageView_star8"
android:layout_width="wrap_content"
android:layout_height="12dp"
android:layout_alignLeft="@+id/imageView_star1"
android:layout_alignTop="@+id/imageView6"
android:src="@drawable/star" />
<LinearLayout
android:id="@+id/middleSurface"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
</LinearLayout>
最佳答案
下面的代码在 Canvas 上绘制了一种颜色。
canvas.drawColor(Color.argb(0, 0, 0, 0)); //To make canvas transparent
我假设你之前画过黑色。这将绘制黑色，然后是新的粒子位置。也就是在绘制之间清除 Canvas 。
现在您在两次绘制之间在 Canvas 上进行了清晰的绘制，实际上您什么也没做。因为什么都不画没有效果。
您实际需要做的是清除 Canvas 。
你需要使用代码:
canvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.CLEAR);
这绘制透明，但也告诉它不要与现有粒子合并，而是实际清除它们:) 引用:https://stackoverflow.com/a/10882301/940834
关于android - 使 Canvas 透明，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/25075712/