The file containing the source code shown below is located in the corresponding directory in <sdk>/samples/android-<version>/...
/*
* Copyright (C) 2008 The Android开源工程
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.example.android.apis.graphics;
//Need the following import to get access to the app resources, since this
//class is in a sub-package.
import com.example.android.apis.R;
import android.app.Activity;
import android.os.Bundle;
import android.graphics.BitmapFactory;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.widget.LinearLayout;
import android.widget.TextView;
import android.widget.ScrollView;
import android.view.LayoutInflater;
import android.view.View;
import android.content.Context;
import android.util.DisplayMetrics;
import android.util.Log;
/**
* This activity demonstrates various ways density can cause the scaling of
* bitmaps and drawables.
*/
public class DensityActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
final LayoutInflater li = (LayoutInflater)getSystemService(
LAYOUT_INFLATER_SERVICE);
this.setTitle(R.string.density_title);
LinearLayout root = new LinearLayout(this);
root.setOrientation(LinearLayout.VERTICAL);
LinearLayout layout = new LinearLayout(this);
addBitmapDrawable(layout, R.drawable.logo120dpi, true);
addBitmapDrawable(layout, R.drawable.logo160dpi, true);
addBitmapDrawable(layout, R.drawable.logo240dpi, true);
addLabelToRoot(root, "Prescaled bitmap in drawable");
addChildToRoot(root, layout);
layout = new LinearLayout(this);
addBitmapDrawable(layout, R.drawable.logo120dpi, false);
addBitmapDrawable(layout, R.drawable.logo160dpi, false);
addBitmapDrawable(layout, R.drawable.logo240dpi, false);
addLabelToRoot(root, "Autoscaled bitmap in drawable");
addChildToRoot(root, layout);
layout = new LinearLayout(this);
addResourceDrawable(layout, R.drawable.logo120dpi);
addResourceDrawable(layout, R.drawable.logo160dpi);
addResourceDrawable(layout, R.drawable.logo240dpi);
addLabelToRoot(root, "Prescaled resource drawable");
addChildToRoot(root, layout);
layout = (LinearLayout)li.inflate(R.layout.density_image_views, null);
addLabelToRoot(root, "Inflated layout");
addChildToRoot(root, layout);
layout = (LinearLayout)li.inflate(R.layout.density_styled_image_views, null);
addLabelToRoot(root, "Inflated styled layout");
addChildToRoot(root, layout);
layout = new LinearLayout(this);
addCanvasBitmap(layout, R.drawable.logo120dpi, true);
addCanvasBitmap(layout, R.drawable.logo160dpi, true);
addCanvasBitmap(layout, R.drawable.logo240dpi, true);
addLabelToRoot(root, "Prescaled bitmap");
addChildToRoot(root, layout);
layout = new LinearLayout(this);
addCanvasBitmap(layout, R.drawable.logo120dpi, false);
addCanvasBitmap(layout, R.drawable.logo160dpi, false);
addCanvasBitmap(layout, R.drawable.logo240dpi, false);
addLabelToRoot(root, "Autoscaled bitmap");
addChildToRoot(root, layout);
layout = new LinearLayout(this);
addResourceDrawable(layout, R.drawable.logonodpi120);
addResourceDrawable(layout, R.drawable.logonodpi160);
addResourceDrawable(layout, R.drawable.logonodpi240);
addLabelToRoot(root, "No-dpi resource drawable");
addChildToRoot(root, layout);
layout = new LinearLayout(this);
addNinePatchResourceDrawable(layout, R.drawable.smlnpatch120dpi);
addNinePatchResourceDrawable(layout, R.drawable.smlnpatch160dpi);
addNinePatchResourceDrawable(layout, R.drawable.smlnpatch240dpi);
addLabelToRoot(root, "Prescaled 9-patch resource drawable");
addChildToRoot(root, layout);
setContentView(scrollWrap(root));
}
private View scrollWrap(View view) {
ScrollView scroller = new ScrollView(this);
scroller.addView(view, new ScrollView.LayoutParams(ScrollView.LayoutParams.MATCH_PARENT,
ScrollView.LayoutParams.MATCH_PARENT));
return scroller;
}
private void addLabelToRoot(LinearLayout root, String text) {
TextView label = new TextView(this);
label.setText(text);
root.addView(label, new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT,
LinearLayout.LayoutParams.WRAP_CONTENT));
}
private void addChildToRoot(LinearLayout root, LinearLayout layout) {
root.addView(layout, new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT,
LinearLayout.LayoutParams.WRAP_CONTENT));
}
private void addBitmapDrawable(LinearLayout layout, int resource, boolean scale) {
Bitmap bitmap;
bitmap = loadAndPrintDpi(resource, scale);
View view = new View(this);
final BitmapDrawable d = new BitmapDrawable(getResources(), bitmap);
if (!scale) d.setTargetDensity(getResources().getDisplayMetrics());
view.setBackgroundDrawable(d);
view.setLayoutParams(new LinearLayout.LayoutParams(d.getIntrinsicWidth(),
d.getIntrinsicHeight()));
layout.addView(view);
}
private void addResourceDrawable(LinearLayout layout, int resource) {
View view = new View(this);
final Drawable d = getResources().getDrawable(resource);
view.setBackgroundDrawable(d);
view.setLayoutParams(new LinearLayout.LayoutParams(d.getIntrinsicWidth(),
d.getIntrinsicHeight()));
layout.addView(view);
}
private void addCanvasBitmap(LinearLayout layout, int resource, boolean scale) {
Bitmap bitmap;
bitmap = loadAndPrintDpi(resource, scale);
ScaledBitmapView view = new ScaledBitmapView(this, bitmap);
view.setLayoutParams(new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT,
LinearLayout.LayoutParams.WRAP_CONTENT));
layout.addView(view);
}
private void addNinePatchResourceDrawable(LinearLayout layout, int resource) {
View view = new View(this);
final Drawable d = getResources().getDrawable(resource);
view.setBackgroundDrawable(d);
Log.i("foo", "9-patch #" + Integer.toHexString(resource)
+ " w=" + d.getIntrinsicWidth() + " h=" + d.getIntrinsicHeight());
view.setLayoutParams(new LinearLayout.LayoutParams(
d.getIntrinsicWidth()*2, d.getIntrinsicHeight()*2));
layout.addView(view);
}
private Bitmap loadAndPrintDpi(int id, boolean scale) {
Bitmap bitmap;
if (scale) {
bitmap = BitmapFactory.decodeResource(getResources(), id);
} else {
BitmapFactory.Options opts = new BitmapFactory.Options();
opts.inScaled = false;
bitmap = BitmapFactory.decodeResource(getResources(), id, opts);
}
return bitmap;
}
private class ScaledBitmapView extends View {
private Bitmap mBitmap;
public ScaledBitmapView(Context context, Bitmap bitmap) {
super(context);
mBitmap = bitmap;
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
final DisplayMetrics metrics = getResources().getDisplayMetrics();
setMeasuredDimension(
mBitmap.getScaledWidth(metrics),
mBitmap.getScaledHeight(metrics));
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.drawBitmap(mBitmap, 0.0f, 0.0f, null);
}
}
}