Android 未显示图形的自定义视图
我想创建一个包含二维图形(圆形、方形、直线等)的自定义视图 我实现了如下onCreate方法:Android 未显示图形的自定义视图,android,Android,我想创建一个包含二维图形(圆形、方形、直线等)的自定义视图 我实现了如下onCreate方法: @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); LinearLayout layout = new LinearLayout(this);
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
LinearLayout layout = new LinearLayout(this);
LinePlotter lp = new LinePlotter(this, 500, 500);
layout.setLayoutParams(new LinearLayout.LayoutParams(500,500));
layout.addView(lp);
LinearLayout main = findViewById(R.id.linearTest);
main.addView(layout);
}
package com.inti.plottest;
import android.content.Context;
import android.graphics.Canvas;
import android.view.View;
public class LinePlotter extends View {
private int WIDTH;
private int HEIGHT;
public LinePlotter(Context context, int width, int height) {
super(context);
WIDTH = width;
HEIGHT = height;
}
@Override
public void onDraw(Canvas canvas){
System.err.println("Por aca pase");
canvas.drawColor(5614080);
}
}
我的线型绘图仪类是这样的:
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
LinearLayout layout = new LinearLayout(this);
LinePlotter lp = new LinePlotter(this, 500, 500);
layout.setLayoutParams(new LinearLayout.LayoutParams(500,500));
layout.addView(lp);
LinearLayout main = findViewById(R.id.linearTest);
main.addView(layout);
}
package com.inti.plottest;
import android.content.Context;
import android.graphics.Canvas;
import android.view.View;
public class LinePlotter extends View {
private int WIDTH;
private int HEIGHT;
public LinePlotter(Context context, int width, int height) {
super(context);
WIDTH = width;
HEIGHT = height;
}
@Override
public void onDraw(Canvas canvas){
System.err.println("Por aca pase");
canvas.drawColor(5614080);
}
}
首先,我想看到的是按钮(activity_main.xml的一部分)正下方的500x500 px正方形,我添加它只是为了防止出现问题
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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:id="@+id/mainLayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity" >
<LinearLayout
android:id="@+id/linearTest"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
<Button
android:id="@+id/btnTest"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:onClick="onDoTestClicked"
android:text="Button" />
</LinearLayout>
</androidx.constraintlayout.widget.ConstraintLayout>
但是它仍然没有显示。您的视图没有任何大小,请尝试在LayoutSpector中检查它。 您必须重写onMeasure方法,并通过调用
设置测量尺寸(宽度、高度)
这里有一篇详细的好文章
编辑:也可以将颜色更改为正确的颜色,例如canvas.drawColor(Color.BLUE)尝试在
LinePlotter
视图而不是父视图上设置LayoutParams
。@aarelovich请检查我的编辑,您的代码中有错误的颜色