Thứ Ba, 4 tháng 9, 2012

Custom View

0
06:48
It's a very basic custom view extends android.view.View; simple draw background and a cross across the view. We will do more exercises base on it in coming posts.

Custom View


Create a custom view, MyView.java extends View.
package com.example.androiddraw;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.View;

public class MyView extends View {

Paint BackPaint = new Paint();
Paint MyPaint = new Paint();
Context MyContext;

public MyView(Context context) {
super(context);
init(context);
}

public MyView(Context context, AttributeSet attrs) {
super(context, attrs);
init(context);
}

public MyView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init(context);
}

private void init(Context ctx){
MyContext = ctx;

BackPaint.setStyle(Paint.Style.FILL);
BackPaint.setColor(Color.GRAY);

MyPaint.setStyle(Paint.Style.STROKE);
MyPaint.setColor(Color.WHITE);
MyPaint.setStrokeWidth(3);
}

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
int w = MeasureSpec.getSize(widthMeasureSpec);
int h = MeasureSpec.getSize(heightMeasureSpec);
setMeasuredDimension(w, h);
}

@Override
protected void onDraw(Canvas canvas) {
canvas.drawRect(0, 0, getWidth(), getHeight(), BackPaint);
canvas.drawLine(0, 0, getWidth(), getHeight(), MyPaint);
canvas.drawLine(getWidth(), 0, 0, getHeight(), MyPaint);
};

}


Modify the main code, MainActivity.java, to set it in ContentView.
package com.example.androiddraw;

import android.os.Bundle;
import android.app.Activity;

public class MainActivity extends Activity {

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);

MyView myView = new MyView(this);
setContentView(myView);
}

}


Download the files.


Related examples:
- Paint.setShader() with SweepGradient
- LinearGradient example
- Draw bitmap on canvas
- Draw text with shadow on canvas
- Draw bitmap with shadow on canvas
- RadialGradient example
- Using ColorMatrixColorFilter
- Generate negative image using ColorMatrix
- LightingColorFilter example
- PorterDuffColorFilter example


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