我想画一个矩形。第一个角应该是用户第一次触摸屏幕的地方。当用户移动他的手指时,它应该绘制矩形。这是 a link显示我想做什么的视频。但我不明白,也许你可以帮助我。我只想在白色背景上而不是图像上绘制该矩形。
我的代码:
package com.example.androiddrawing;
import java.util.ArrayList;
import java.util.List;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.Point;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
public class CanvasView extends View {
private Canvas canvas;
private Paint paint = new Paint();
private Paint paint2 = new Paint();
private Paint paint3 = new Paint();
private Path path = new Path();
private Point point = new Point();
private static List<Path> lines = new ArrayList<Path>();
private static List<Point> points = new ArrayList<Point>();
private float x, x2, xc, xd, x3, x4;
private float y, y2, yc, yd, y3, y4;
private boolean touchStarted = false;
public enum DrawMode {
FreeDrawMode, RectDrawMode
};
public static DrawMode currentDrawMode;
public void setDrawMode(DrawMode newDrawMode) {
this.currentDrawMode = newDrawMode;
}
public CanvasView(Context context, AttributeSet attrs) {
super(context, attrs);
paint.setAntiAlias(true);
paint.setStrokeWidth(5);
paint.setColor(Color.BLACK);
paint.setStyle(Paint.Style.STROKE);
paint.setStrokeJoin(Paint.Join.ROUND);
paint2.setAntiAlias(true);
paint2.setStrokeWidth(5);
paint2.setColor(Color.RED);
paint2.setStyle(Paint.Style.STROKE);
paint2.setStrokeJoin(Paint.Join.ROUND);
paint3.setAntiAlias(true);
paint3.setColor(Color.BLACK);
paint3.setStrokeWidth(10);
paint3.setStyle(Paint.Style.STROKE);
}
@Override
protected void onDraw(Canvas canvas) {
for (Path p : lines)
canvas.drawPath(p, paint);
canvas.drawPath(path, paint2);
for (Point point : points)
canvas.drawCircle(point.x, point.y, 0, paint);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
x = event.getX();
y = event.getY();
System.out.println(currentDrawMode);
if (currentDrawMode == DrawMode.FreeDrawMode) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
// Set a new starting point
paint2.setColor(Color.RED);
path = new Path();
path.moveTo(x, y);
touchStarted = true;
break;
// return true;
case MotionEvent.ACTION_MOVE:
// Connect the points
touchStarted = false;
path.lineTo(x, y);
break;
case MotionEvent.ACTION_UP:
if (touchStarted) {
point = new Point();
point.x = (int) x;
point.y = (int) y;
paint2.setColor(Color.BLACK);
points.add(point);
touchStarted = false;
System.out.println("siin");
} else {
System.out.println("seal");
paint2.setColor(Color.BLACK);
lines.add(path);
}
break;
default:
return false;
}
} else if (currentDrawMode == DrawMode.RectDrawMode) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
// Set a new starting point
paint3.setColor(Color.RED);
//CODE HERE
break;
// return true;
case MotionEvent.ACTION_MOVE:
//CODE HERE
break;
case MotionEvent.ACTION_UP:
//CODE HERE
break;
default:
return false;
}
}
// Makes our view repaint and call onDraw
invalidate();
return true;
}
}
我应该在注释//CODE HERE 的地方写代码,但我真的不明白,我必须如何绘制一个矩形。
最佳答案
您可以使用以下代码。希望对您有所帮助。
public class DrawSample extends View {
int mStartX;
int mStartY;
int mEndX;
int mEndY;
Paint mPaint = new Paint();
int mSelectedColor = Color.BLACK;
public DrawSample(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
mPaint.setColor(mSelectedColor);
mPaint.setStrokeWidth(5);
mPaint.setStyle(Paint.Style.STROKE);
setFocusable(true);
}
public DrawSample(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
switch (event.getActionMasked()) {
case MotionEvent.ACTION_DOWN:
mStartX = (int) event.getX();
mStartY = (int) event.getY();
break;
case MotionEvent.ACTION_MOVE:
mEndX = (int) event.getX();
mEndY = (int) event.getY();
invalidate();
break;
case MotionEvent.ACTION_UP:
mEndX = (int) event.getX();
mEndY = (int) event.getY();
invalidate();
break;
default:
super.onTouchEvent(event);
break;
}
return true;
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.drawRect(mStartX, mStartY, mEndX, mEndY, mPaint);
}
}
关于java - 用户移动手指时如何在android中绘制矩形?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/26869822/