我正在制作Android应用程序而且我有一件棘手的事情要做。 我需要在画布上绘制一条路径，但绘图应该是动画的（即稍微延迟后绘制点）。
是否可以使用Android SDK制作类似的内容？ 如果没有，我怎么能产生这种效果？
答案 0 :(得分：31)
尝试使用此代码，我用它来使用Path＆amp; Canvas：
public class TestActivity extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(new HeartbeatView(this));
}
public static class HeartbeatView extends View {
private static Paint paint;
private int screenW, screenH;
private float X, Y;
private Path path;
private float initialScreenW;
private float initialX, plusX;
private float TX;
private boolean translate;
private int flash;
private Context context;
public HeartbeatView(Context context) {
super(context);
this.context=context;
paint = new Paint();
paint.setColor(Color.argb(0xff, 0x99, 0x00, 0x00));
paint.setStrokeWidth(10);
paint.setAntiAlias(true);
paint.setStrokeCap(Paint.Cap.ROUND);
paint.setStrokeJoin(Paint.Join.ROUND);
paint.setStyle(Paint.Style.STROKE);
paint.setShadowLayer(7, 0, 0, Color.RED);
path= new Path();
TX=0;
translate=false;
flash=0;
}
@Override
public void onSizeChanged (int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
screenW = w;
screenH = h;
X = 0;
Y = (screenH/2)+(screenH/4)+(screenH/10);
initialScreenW=screenW;
initialX=((screenW/2)+(screenW/4));
plusX=(screenW/24);
path.moveTo(X, Y);
}
@Override
public void onDraw(Canvas canvas) {
super.onDraw(canvas);
//canvas.save();
flash+=1;
if(flash<10 || (flash>20 && flash<30))
{
paint.setStrokeWidth(16);
paint.setColor(Color.RED);
paint.setShadowLayer(12, 0, 0, Color.RED);
}
else
{
paint.setStrokeWidth(10);
paint.setColor(Color.argb(0xff, 0x99, 0x00, 0x00));
paint.setShadowLayer(7, 0, 0, Color.RED);
}
if(flash==100)
{
flash=0;
}
path.lineTo(X,Y);
canvas.translate(-TX, 0);
if(translate==true)
{
TX+=4;
}
if(X<initialX)
{
X+=8;
}
else
{
if(X<initialX+plusX)
{
X+=2;
Y-=8;
}
else
{
if(X<initialX+(plusX*2))
{
X+=2;
Y+=14;
}
else
{
if(X<initialX+(plusX*3))
{
X+=2;
Y-=12;
}
else
{
if(X<initialX+(plusX*4))
{
X+=2;
Y+=6;
}
else
{
if(X<initialScreenW)
{
X+=8;
}
else
{
translate=true;
initialX=initialX+initialScreenW;
}
}
}
}
}
}
canvas.drawPath(path, paint);
//canvas.restore();
invalidate();
}
}
}
它使用使用计数器逐点绘制路径和一对效果。您可以将所需内容转移到SurfaceView，效率更高。
答案 1 :(得分：3)
我希望这就是你要找的东西。它描绘了用户触摸的路径，你可以简单地调整它以达到你想要的效果。
public class MyCanvas extends Activity implements OnTouchListener{
DrawPanel dp;
private ArrayList<Path> pointsToDraw = new ArrayList<Path>();
private Paint mPaint;
Path path;
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
dp = new DrawPanel(this);
dp.setOnTouchListener(this);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,WindowManager.LayoutParams.FLAG_FULLSCREEN);
requestWindowFeature(Window.FEATURE_NO_TITLE);
mPaint = new Paint();
mPaint.setDither(true);
mPaint.setColor(Color.WHITE);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeJoin(Paint.Join.ROUND);
mPaint.setStrokeCap(Paint.Cap.ROUND);
mPaint.setStrokeWidth(30);
FrameLayout fl = new FrameLayout(this);
fl.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));
fl.addView(dp);
setContentView(fl);
}
@Override
protected void onPause() {
// TODO Auto-generated method stub
super.onPause();
dp.pause();
}
@Override
protected void onResume() {
// TODO Auto-generated method stub
super.onResume();
dp.resume();
}
public class DrawPanel extends SurfaceView implements Runnable{
Thread t = null;
SurfaceHolder holder;
boolean isItOk = false ;
public DrawPanel(Context context) {
super(context);
// TODO Auto-generated constructor stub
holder = getHolder();
}
@Override
public void run() {
// TODO Auto-generated method stub
while( isItOk == true){
if(!holder.getSurface().isValid()){
continue;
}
Canvas c = holder.lockCanvas();
c.drawARGB(255, 0, 0, 0);
onDraw(c);
holder.unlockCanvasAndPost(c);
}
}
@Override
protected void onDraw(Canvas canvas) {
// TODO Auto-generated method stub
super.onDraw(canvas);
synchronized(pointsToDraw)
{
for (Path path : pointsToDraw) {
canvas.drawPath(path, mPaint);
}
}
}
public void pause(){
isItOk = false;
while(true){
try{
t.join();
}catch(InterruptedException e){
e.printStackTrace();
}
break;
}
t = null;
}
public void resume(){
isItOk = true;
t = new Thread(this);
t.start();
}
}
@Override
public boolean onTouch(View v, MotionEvent me) {
// TODO Auto-generated method stub
synchronized(pointsToDraw)
{
if(me.getAction() == MotionEvent.ACTION_DOWN){
path = new Path();
path.moveTo(me.getX(), me.getY());
//path.lineTo(me.getX(), me.getY());
pointsToDraw.add(path);
}else if(me.getAction() == MotionEvent.ACTION_MOVE){
path.lineTo(me.getX(), me.getY());
}else if(me.getAction() == MotionEvent.ACTION_UP){
//path.lineTo(me.getX(), me.getY());
}
}
return true;
}
}
答案 2 :(得分：1)
我是用 ObjectAnimator 制作的。 我们有任何路径和自定义视图（我们将在其中绘制路径）
private CustomView view;
private Path path;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
view = findViewById(R.id.custom_view);
path = new Path();
path.moveTo(0f, 0f);
path.lineTo(getResources().getDimension(R.dimen.point_250), 0f);
path.lineTo(getResources().getDimension(R.dimen.point_250), getResources().getDimension(R.dimen.point_150));
findViewById(R.id.btnStart).setOnClickListener(v -> {
test();
});
}
private void test() {
ValueAnimator pathAnimator = ObjectAnimator.ofFloat(view, "xCoord", "yCoord", path);
pathAnimator.setDuration(5000);
pathAnimator.start();
}
然后将我们的“xCoord”和“yCoord”传递给CustomView
public class CustomView extends View {
private Paint paint;
private float xCoord;
private float yCoord;
private Path path = new Path();
public void setXCoord(float xCoord) {
this.xCoord = xCoord;
}
public void setYCoord(float yCoord) {
this.yCoord = yCoord;
path.lineTo(xCoord, yCoord);
invalidate();
}
public CustomView(Context context) {
super(context);
init();
}
public CustomView(Context context, @Nullable AttributeSet attrs) {
super(context, attrs);
init();
}
void init() {
paint = new Paint();
paint.setAntiAlias(true);
paint.setDither(true);
paint.setColor(Color.BLACK);
paint.setStyle(Paint.Style.STROKE);
paint.setStrokeJoin(Paint.Join.ROUND);
paint.setStrokeCap(Paint.Cap.ROUND);
paint.setStrokeWidth(20);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.drawPath(path, paint);
}
}
答案 3 :(得分：0)
这可能会有所帮助......它会绘制相邻的圆圈而不是模拟可动画路径的路径。
public class PathAnimatable {
private final float CIRCLE_SIZE = 2.5f;
public float SPPED_SCALE = 1f;
private float steps = 0;
private float pathLength;
private PathMeasure pathMeasure;
private float totalStepsNeeded;
private float[] point = new float[]{0f, 0f};
private float stride;
public PathAnimatable() {
this(null);
}
public PathAnimatable(Path path) {
super(path);
init();
}
private void init() {
pathMeasure = new PathMeasure(path, false);
pathLength = pathMeasure.getLength();
stride = CIRCLE_SIZE * 0.5f;
totalStepsNeeded = pathLength / stride;
steps = 0;
}
@Override
public void setPath(Path path) {
super.setPath(path);
init();
}
// Called this from your locked canvas loop function
public void drawShape(Canvas canvas, Paint paint) {
if (steps <= pathLength) {
for (float i = 0; i < steps ; i += stride) {
pathMeasure.getPosTan(i, point, null);
canvas.drawCircle(point[0], point[1], CIRCLE_SIZE, paint);
}
steps += stride * SPPED_SCALE;
} else {
steps = 0;
}
}
}