Android example source code file (DensityActivity.java)

This example Android source code file (DensityActivity.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" ^TM.

Java - Android tags/keywords

activity, android, autoscaled, bitmap, bitmapdrawable, drawing, graphics, inflated, layout_inflater_service, layoutinflater, linearlayout, override, paint, prescaled, scaledbitmapview, scrollview, textview, ui, view, widget

The DensityActivity.java Android example source code

/*
 * Copyright (C) 2008 The Android Open Source Project
 *
 * 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);
        }
    }
}