我在已缩放的画布上绘制文本时遇到问题。我想缩放画布,使绘图尺寸和坐标始终在 0.0 到 1.0 的范围内,即独立于画布的宽度和高度。(如果这是不好的做法,请随时发表评论,说明为什么会这样。)虽然我可以在缩放的画布上正确绘制线条和弧线,但我在绘制文本时遇到了很大的困难,而且这个问题似乎只发生在 Android 上4.2
例如,我在这里创建了一些基于此页面的代码。然而,为了清楚起见,我删除了很多代码。
首先,此代码可以正常工作,并且与上面的链接一样(尽管已精简):
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.DashPathEffect;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.Rect;
import android.os.Bundle;
import android.view.View;
public class DrawDemo extends Activity {
DemoView demoview;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
demoview = new DemoView(this);
setContentView(demoview);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
private class DemoView extends View{
private int width = 0;
private int height = 0;
public DemoView(Context context){
super(context);
}
@Override
protected void onSizeChanged (int w, int h, int oldw, int oldh){
width = w;
height = h;
}
@Override protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
// custom drawing code here
// remember: y increases from top to bottom
// x increases from left to right
int x = 0;
int y = 0;
Paint paint = new Paint();
paint.setStyle(Paint.Style.FILL);
// make the entire canvas white
paint.setColor(Color.WHITE);
canvas.drawPaint(paint);
// draw some text using STROKE style
paint.setStyle(Paint.Style.STROKE);
paint.setStrokeWidth(1);
paint.setColor(Color.MAGENTA);
paint.setTextSize(30);
canvas.drawText("Style.STROKE", 75, 75, paint);
}
}
}
接下来,我将绝对像素大小替换为标准化(0 到 1.0)值并缩放画布:
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.DashPathEffect;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.Rect;
import android.os.Bundle;
import android.view.View;
public class DrawDemo extends Activity {
DemoView demoview;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
demoview = new DemoView(this);
setContentView(demoview);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
private class DemoView extends View{
private int width = 0;
private int height = 0;
public DemoView(Context context){
super(context);
}
@Override
protected void onSizeChanged (int w, int h, int oldw, int oldh){
width = w;
height = h;
}
@Override protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
// custom drawing code here
// remember: y increases from top to bottom
// x increases from left to right
int x = 0;
int y = 0;
Paint paint = new Paint();
paint.setStyle(Paint.Style.FILL);
// make the entire canvas white
paint.setColor(Color.WHITE);
canvas.drawPaint(paint);
// draw some text using STROKE style
canvas.scale(width, height);
paint.setStyle(Paint.Style.STROKE);
//paint.setStrokeWidth(1);
paint.setColor(Color.MAGENTA);
paint.setTextSize(0.2f);
canvas.drawText("Style.STROKE", 0.5f, 0.5f, paint);
}
}
}
结果是屏幕上什么也没有出现。有人可以建议我做错了什么吗?请记住,后者在 Android < 4.2 上对我有用。为代码示例的格式道歉,我仍然无法掌握 Stackoverflows 代码格式。