scene

In Android, the brush uses the Paint class, and the Canvas uses the Canvas class to represent it.

Basic steps of drawing

First, write a custom view class inherited from view, then rewrite its onDraw method, and finally add the custom view to actvity.

Effect

Note:

Blog:
https://blog.csdn.net/badao_liumang_qizhi
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Realization

First, add an id to the layout file of the Activity to be displayed.

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/forever"
    tools:context=".CanvasActivity">

</FrameLayout>

Then create a new custom View class under the package. Here, MyView makes it inherit the View class and writes a construction method with one parameter and rewrites the onDraw method.

In the redraw onDraw method, create a new brush and set some properties, then use the brush to draw a rectangle at the location specified on the canvas. package com.badao.alarmmanager;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.view.View;

public class MyView extends View {
    public MyView(Context context) {
        super(context);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        //Define Brush
        Paint paint = new Paint();
        //Set color
        paint.setColor(0xFFFF6600);
        //Set brush type
        paint.setStyle(Paint.Style.FILL);
        //Using a brush to draw a rectangle on the canvas
        canvas.drawRect(10,10,280,150,paint);

    }
}

Then add this custom view to the activity

package com.badao.alarmmanager;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.widget.FrameLayout;

public class CanvasActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_canvas);
        FrameLayout frameLayout = (FrameLayout) findViewById(R.id.forever);
        frameLayout.addView(new MyView(this));
    }
}