如何使android的画布2D图形过渡 [英] How to make 2D graphic transition in android canvas
本文介绍了如何使android的画布2D图形过渡的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我在使用油漆
和画布
画了一个圈在机器人
。
I have draw a circle using paint
and canvas
in android
.
我想移动的圆圈在某些方向,是否有可以使用任何API方法?还是我必须使用循环和改变位置每次?
I want to move the circle in some direction, are there any API methods that can be used ? Or do I have to use a loop and changing the position each time?
推荐答案
你可以参考code以下,在onTouchEvent,你可以处理的方向和移动的对象。
Hi you can refer the code below, In onTouchEvent, you can handle directions and move the object.
// Tutorial2D.java主要活动
// Tutorial2D.java main activity
import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;
import android.view.Window;
public class Tutorial2D extends Activity {
Square drawView;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
drawView = new Square(this);
drawView.setBackgroundColor(Color.WHITE);
setContentView(drawView);
}
}
// Square.java
// Square.java
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.view.MotionEvent;
import android.view.View;
class Square extends View {
Bitmap mBitmap;
Paint paint = new Paint();
public Square(Context context) {
super(context);
}
@Override
public void onDraw(Canvas canvas) {
canvas.rotate(direction, mCenterX, mCenterY);
paint.setColor(Color.BLACK);
paint.setStrokeWidth(3);
canvas.drawRect(230, 230, 280, 280, paint);
paint.setStrokeWidth(0);
paint.setColor(Color.CYAN);
canvas.drawRect(233, 260, 277, 277, paint);
paint.setColor(Color.YELLOW);
canvas.drawRect(233, 233, 277, 260, paint);
}
private float mCenterX, mCenterY;
private float direction = 0;
private float sX, sY;
private float startDirection = 0;
private void touchStart(float x, float y) {
mCenterX = this.getWidth() / 2;
mCenterY = this.getHeight() / 2;
sX = x;
sY = y;
}
private void touchMove(float x, float y) {
// this calculate the angle the image rotate
float angle = (float) angleBetween2Lines(mCenterX, mCenterY, sX, sY, x,
y);
direction = (float) Math.toDegrees(angle) * -1 + startDirection;
this.invalidate();
}
@Override
public boolean onTouchEvent(MotionEvent event) {
float x = event.getX();
float y = event.getY();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
// record the start position of finger
touchStart(x, y);
break;
case MotionEvent.ACTION_MOVE:
// update image angle
touchMove(x, y);
break;
case MotionEvent.ACTION_UP:
startDirection = direction;
break;
}
return true;
}
public double angleBetween2Lines(float centerX, float centerY, float x1,
float y1, float x2, float y2) {
double angle1 = Math.atan2(y1 - centerY, x1 - centerX);
double angle2 = Math.atan2(y2 - centerY, x2 - centerX);
return angle1 - angle2;
}
}
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