我是android编程的新手。我试图在每次用户触摸屏幕时绘制一个新的位图图像。现在使用当前代码，它所做的就是更改位图所在的位置。它不会成为一个新的。我怎么能换新的？这是代码：
public class MainDrawingView extends View {
public float eventX;
public float eventY;
public AlertDialog.Builder alertThing;
Context context = getContext();
//Bitmaps
public Bitmap redSquare;
public String x;
public String y;
//Colors
public boolean red = false;
public boolean blue = false;
//Squares
public boolean topRight = false;
public boolean topLeft = false;
public boolean bottomLeft = false;
public boolean bottomRight = false;
public int width = context.getResources().getDisplayMetrics().widthPixels;
public int height = context.getResources().getDisplayMetrics().heightPixels;
public int center = height/2;
public int widthDiv = width/2;
private Paint paint = new Paint();
private Point pointStart = new Point();
private Point pointEnd = new Point();
public MainDrawingView(Context context, AttributeSet attrs){
super(context, attrs);
paint.setAntiAlias(true);
paint.setStrokeWidth(5f);
paint.setColor(Color.BLACK);
paint.setStyle(Paint.Style.STROKE);
paint.setStrokeJoin(Paint.Join.ROUND);
alertThing = new AlertDialog.Builder(context);
//define bitmap
redSquare = BitmapFactory.decodeResource(getResources(), R.drawable.red);
}
@Override
public void onDraw(Canvas canvas){
//canvas.drawPath(path, paint);
canvas.drawLine(pointStart.x, pointStart.y, pointEnd.x, pointEnd.y,paint);
//Makes a straight line go through the center of the screen.
canvas.drawLine(0,height/2.5f, width,height/2.5f,paint);
//Makes a straight line go up and down.
canvas.drawLine(width/2.3f,0, width/2.3f, height,paint);
//Chnages the square colors.
// top left combo
if(topLeft){
if(red){
Toast.makeText(context,"jgjgjgjgjgjgjgjgjjg", Toast.LENGTH_SHORT).show();
new Drawings(redSquare, canvas, eventX, eventY);
}
}
}
@Override
public boolean onTouchEvent(MotionEvent event){
//Gets the coords of the tap
eventX = event.getX();
eventY = event.getY();
int pointX = Math.round(eventX);
int pointY = Math.round(eventY);
x = String.valueOf(eventX);
y = String.valueOf(eventY);
//This is the top left "square"
if(eventY < center && eventX < widthDiv ){
alertThing.setTitle("edit square");
alertThing.setMessage("please choose an option");
alertThing.setPositiveButton("red", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
topLeft = true;
red = true;
invalidate();
}
});
alertThing.setNeutralButton("Chnange color to blue", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
}
});
alertThing.create();
alertThing.show();
}
Toast.makeText(context, "center is :" +x, Toast.LENGTH_SHORT ).show();
switch(event.getAction()){
case MotionEvent.ACTION_DOWN:
//Sets a new starting point
pointStart.set(pointX,pointY);
return true;
case MotionEvent.ACTION_UP:
//Contects the points
pointEnd.set(pointX,pointY);
break;
default:
return false;
}
invalidate();
return true;
}
}
这是绘制位图的Drawings类：
public class Drawings {
public Drawings(Bitmap bitmap, Canvas canvas,float x, float y){
canvas.drawBitmap(bitmap, x,y,null);
}
}
答案 0 :(得分：1)