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我開發了一個應用程序，它使用屏幕作爲石板和手指作爲粉筆，這是正常工作。但我想用不同顏色的粉筆。如何在應用程序中添加拾色器？
這裏是我的代碼：
MyDemo.java
package com.example.mydemo;
import android.os.Bundle;
import android.app.Activity;
import android.view.View;
import android.widget.Button;
import android.widget.LinearLayout;
public class MyDemo extends Activity {
private LinearLayout root;
private Button btnReset;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_my_demo);
root = (LinearLayout) findViewById(R.id.root);
btnReset = (Button) findViewById(R.id.reset);
final MyImageView view = new MyImageView(this);
view.setLayoutParams(new LinearLayout.LayoutParams(LinearLayout.LayoutParams.FILL_PARENT, LinearLayout.LayoutParams.FILL_PARENT));
root.addView(view);
btnReset.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
view.reset();
}
});
}
}
MyImageView.java
package com.example.mydemo;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.PointF;
import android.view.MotionEvent;
import android.view.View;
import android.widget.ImageView;
import java.util.ArrayList;
import java.util.List;
public class MyImageView extends ImageView implements View.OnTouchListener {
private int id = -1;
private Path path;
private List<Path> paths = new ArrayList<Path>();
private List<PointF> points = new ArrayList<PointF>();
boolean multiTouch = false;
public MyImageView(Context context) {
super(context);
this.setOnTouchListener(this);
}
public void reset() {
paths.clear();
points.clear();
path = null;
id = -1;
invalidate();
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
Paint paint = createPen(Color.BLACK);
paint.setStyle(Paint.Style.STROKE);
for (Path path : paths) {
canvas.drawPath(path, paint);
}
for (int i = 0; i < points.size(); i++) {
PointF p = points.get(i);
canvas.drawText("" + p.x, p.y, i, createPen(Color.WHITE));
}
}
private PointF copy(PointF p) {
PointF copy = new PointF();
copy.set(p);
return copy;
}
public boolean onTouch(View v, MotionEvent event) {
int action = event.getAction();
switch (action & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN:
multiTouch = false;
id = event.getPointerId(0);
PointF p = getPoint(event, id);
path = new Path();
path.moveTo(p.x, p.y);
paths.add(path);
points.add(copy(p));
break;
case MotionEvent.ACTION_POINTER_DOWN:
multiTouch = true;
for (int i = 0; i < event.getPointerCount(); i++) {
int tId = event.getPointerId(i);
if (tId != id) {
points.add(getPoint(event,i));
}
}
break;
case MotionEvent.ACTION_MOVE:
if (!multiTouch) {
p =getPoint(event, id);
path.lineTo(p.x, p.y);
}
break;
}
invalidate();
return true;
}
private PointF getPoint(MotionEvent event, int i) {
int index = 0;
return new PointF(event.getX(index), event.getY(index));
}
private Paint createPen(int color) {
Paint pen = new Paint();
pen.setColor(color);
float width = 3;
pen.setStrokeWidth(width);
return pen;
}
}
activity_my_demo.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout android:id="@+id/root" xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<Button android:id="@+id/reset" android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Reset"
/>
</LinearLayout>
任何人都可以告訴我應該在代碼中添加或更改哪些內容，以便我可以爲Chalk使用不同的顏色？