So basically i want to use a xml layout, but i also want a canvas where i can have graphics performed. What i did was make a view in my xml layout as you can see below. Then in my application i made the view draw the canvas, but it is not working. I'm not sure if my method for solving this is completely wrong or what. So please just take a look at my code and tell me if you see a quick fix or if you have a better method. Thanks in advance I really appreciate it.
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<Button
android:id="@+id/bTest"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button" />
<View
android:id="@+id/vMain"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</LinearLayout>
that is the xml layout
package sm.view.test;
import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Paint.Align;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.View.OnTouchListener;
import android.widget.Button;
public class ViewActivity extends Activity implements OnTouchListener {
/** Called when the activity is first created. */
View v;
Button b;
boolean isRun =true;
SurfaceHolder ourHolder;
Thread ourThread;
Canvas canvas;
boolean isTure = true;
TheSurface ourSurfaceView;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
b= (Button) findViewById(R.id.bTest);
v = (View) findViewById(R.id.vMain);
canvas = new Canvas();
ourSurfaceView = new TheSurface(this);
ourSurfaceView.setOnTouchListener(this);
v.draw(canvas);
// v.setBackgroundColor(Color.BLUE);
}
protected void onPause() {
// TODO Auto-generated method stub
super.onPause();
ourSurfaceView.pause();
}
@Override
protected void onResume() {
// TODO Auto-generated method stub
super.onResume();
ourSurfaceView.resume();
}
public boolean onTouch(View arg0, MotionEvent arg1) {
// TODO Auto-generated method stub
return false;
}
public class TheSurface extends SurfaceView implements Runnable{
public TheSurface(Context context) {
super(context);
ourHolder= getHolder();
}
public void resume(){
isRun= true;
ourThread = new Thread(this);
ourThread.start();
}
public void pause(){
isRun = false;
while(true){
try {
ourThread.join();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
break;
}
ourThread= null;
}
public void run() {
// TODO Auto-generated method stub
Paint textPaint = new Paint();
textPaint.setColor(Color.WHITE);
while(isTure){
if(!ourHolder.getSurface().isValid())
continue;
//v.draw(canvas);
canvas = ourHolder.lockCanvas();
canvas.drawLine(0, 0, canvas.getWidth(), canvas.getHeight(), textPaint);
ourHolder.unlockCanvasAndPost(canvas);
v.draw(canvas);
}
}
}
}
Start here (and this needs your input as well for the namespace portion "yourProjectNamespace"):
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<Button android:id="@+id/bTest"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button" />
<sm.view.test.TheSurface android:id="@+id/vMain"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</LinearLayout>
In your TheSurface
Implement the overideable routines:
public TheSurface(Context C){
super(C);
// Other setup code you want here
}
public TheSurface(Context C, AttributeSet attribs){
super(C, attribs);
// Other setup code you want here
}
public TheSurface(Context C, AttributeSet attribs, int defStyle){
super(C, attribs, defStyle);
// Other setup code you want here
}
protected void onDraw(Canvas canvas){
super.onDraw(canvas);
Paint textPaint = new Paint();
textPaint.setColor(Color.WHITE);
canvas.drawLine(0, 0, canvas.getWidth(), canvas.getHeight(), textPaint);
// Other drawing functions here!!!
}
This should get your drawing done!!!
Also in my case, you dont have to implement this as a SurfaceView, you could just implement it as a View, and it does not need to implement runnable!!!
I'm not 100% sure I understand what you are trying to do, but based on the fact that you don't seem to be doing anything with the canvas after you call View.draw() I believe you may be confused. View.draw(Canvas) draws the View onto the Canvas, it doesn't alter the view.
However, if you create the canvas from a bitmap you could then set the bitmap as an ImageView's image:
Bitmap bm = Bitmap.createBitmap( x-size, y-size, Config.ARGB_8888);
Canvas c = new Canvas(bm);
Paint textPaint = new Paint();
textPaint.setColor(Color.WHITE);
canvas.drawLine(0, 0, canvas.getWidth(), canvas.getHeight(), textPaint);
ImageView iView = (ImageView) view;
iView.setImageBitmap(bm);
However, this is a less correct way than to implement your own View:
button.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View view) {
((MyView)view).mContextVariable = true; //or false, etc
//you might not need this invalidate, because the click event probably causes and invalidate to be called
view.invalidate();
}
}
class MyView extends View
{
Paint myPaint;
boolean mContextVariable;
public MyView(Context context)
{
super(context);
textPaint = new Paint();
textPaint.setColor(Color.WHITE);
}
@Override
protected void onDraw(Canvas canvas)
{
if(mContextVariable)
{
canvas.drawLine(0, 0, canvas.getWidth(), canvas.getHeight(), textPaint);
}
else
{
//draw something else
}
canvas.drawText("testing", 0,0, textPaint);
}
}
来源：https://stackoverflow.com/questions/11162626/android-use-a-view-from-a-xml-layout-to-draw-a-canvas