Programmation Android/Exemples/miniPainter

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Programmation Android
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Objectif[modifier | modifier le wikicode]

Le but est de réaliser un mini logiciel de dessin pour Android. Le code est celui de l'ancien fingerpaint pour android 1.1.

Réalisation[modifier | modifier le wikicode]

MainActivity.java[modifier | modifier le wikicode]

Pour dessiner on a besoin de 4 éléments :

  • Bitmap qui regroupe les pixels définissant le trait
  • Canvas qui doit contenir tous les traits
  • Path : une Primitive (le trait lui même)
  • Paint pour décrire la couleur et le style du dessin

Le path est une courbe de bézier qui trace le bitmap.

/*
 * Copyright (C) 2007 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.fingerpaint;

import android.app.*;
import android.content.Context;
import android.graphics.*;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.MotionEvent;
import android.view.View;

public class MainActivity extends Activity
        implements ColorPickerDialog.OnColorChangedListener {

    private Paint mPaint;
    private MaskFilter  mEmboss;
    private MaskFilter  mBlur;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(new MyView(this));

        // creation d'un objet paint
        mPaint = new Paint();
        // customization du paint
        mPaint.setAntiAlias(true);
        mPaint.setDither(true);
        mPaint.setColor(0xFFFF0000);
        mPaint.setStyle(Paint.Style.STROKE);
        mPaint.setStrokeJoin(Paint.Join.ROUND);
        mPaint.setStrokeCap(Paint.Cap.ROUND);
        mPaint.setStrokeWidth(12);

        // modification des propriétés sur la brosse
        mEmboss = new EmbossMaskFilter(new float[] { 1, 1, 1 },
                                       0.4f, 6, 3.5f);
        mBlur = new BlurMaskFilter(8, BlurMaskFilter.Blur.NORMAL);
    }

    // permet d'assigner la couleur à l'objet paint
    public void colorChanged(int color) {
        mPaint.setColor(color);
    }

    public class MyView extends View {

        // 
        private static final float MINP = 0.25f;
        private static final float MAXP = 0.75f;

        // les 4 éléments de bases pour permettre le dessin
        private Bitmap  mBitmap;
        private Canvas  mCanvas;
        private Path    mPath;
        private Paint   mBitmapPaint;

        public MyView(Context c) {
            super(c);
            // instanciation du path
            mPath = new Path();
            // instanciation du paint avec tramage à on.
            mBitmapPaint = new Paint(Paint.DITHER_FLAG);
        }

        @Override
        protected void onSizeChanged(int w, int h, int oldw, int oldh) {
            super.onSizeChanged(w, h, oldw, oldh);
            // creation du bitmap ou objet du trait
            mBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
            // instanciation du canvas
            mCanvas = new Canvas(mBitmap);
        }

        // methode appelée dynamiquement quand on dessine
        @Override
        protected void onDraw(Canvas canvas) {
            // assignation de la couleur au canvas
            canvas.drawColor(0xFFAAAAAA);
            // assignation du bitmap au canvas
            canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);
            // assignation du chemin au canvas
            canvas.drawPath(mPath, mPaint);
        }

        private float mX, mY;
        // tolérance de la touche
        private static final float TOUCH_TOLERANCE = 4;

        // à la touche posée
        private void touch_start(float x, float y) {
            mPath.reset();
            // deplacement du path et positionnement en x,y
            mPath.moveTo(x, y);
            mX = x;
            mY = y;
        }

        // à la touche en déplacement
        private void touch_move(float x, float y) {
            // approximation du bezier au deplacement
            float dx = Math.abs(x - mX);
            float dy = Math.abs(y - mY);
            if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE) {
                mPath.quadTo(mX, mY, (x + mX)/2, (y + mY)/2);
                mX = x;
                mY = y;
            }
        }

        // a la touche levée
        private void touch_up() {
            mPath.lineTo(mX, mY);
            // dessin du path sur l'objet paint
            mCanvas.drawPath(mPath, mPaint);
            // reset du path pour ne pas avoir le chemin précédent
            mPath.reset();
        }

        // lancement des methodes de touch de l'écran tactile du smartphone
        @Override
        public boolean onTouchEvent(MotionEvent event) {
            // prend l'axe des X
            float x = event.getX();
            // prend l'axe des Y
            float y = event.getY();

            switch (event.getAction()) {
                case MotionEvent.ACTION_DOWN:
                    touch_start(x, y);
                    invalidate();
                    break;
                case MotionEvent.ACTION_MOVE:
                    touch_move(x, y);
                    invalidate();
                    break;
                case MotionEvent.ACTION_UP:
                    touch_up();
                    invalidate();
                    break;
            }
            return true;
        }
    }

    // assignation des ids du menu
    private static final int COLOR_MENU_ID = Menu.FIRST;
    private static final int EMBOSS_MENU_ID = Menu.FIRST + 1;
    private static final int BLUR_MENU_ID = Menu.FIRST + 2;
    private static final int ERASE_MENU_ID = Menu.FIRST + 3;
    private static final int SRCATOP_MENU_ID = Menu.FIRST + 4;

    // assignation des éléments du menu
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        super.onCreateOptionsMenu(menu);

        menu.add(0, COLOR_MENU_ID, 0, "Color").setShortcut('3', 'c');
        menu.add(0, EMBOSS_MENU_ID, 0, "Emboss").setShortcut('4', 's');
        menu.add(0, BLUR_MENU_ID, 0, "Blur").setShortcut('5', 'z');
        menu.add(0, ERASE_MENU_ID, 0, "Erase").setShortcut('5', 'z');
        menu.add(0, SRCATOP_MENU_ID, 0, "SrcATop").setShortcut('5', 'z');

        /****   Is this the mechanism to extend with filter effects?
        Intent intent = new Intent(null, getIntent().getData());
        intent.addCategory(Intent.CATEGORY_ALTERNATIVE);
        menu.addIntentOptions(
                              Menu.ALTERNATIVE, 0,
                              new ComponentName(this, NotesList.class),
                              null, intent, 0, null);
        *****/
        return true;
    }

    @Override
    public boolean onPrepareOptionsMenu(Menu menu) {
        super.onPrepareOptionsMenu(menu);
        return true;
    }

    // événements lancés selon les éléments du menu appelés
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        mPaint.setXfermode(null);
        mPaint.setAlpha(0xFF);

        switch (item.getItemId()) {
            case COLOR_MENU_ID:
                // ouverture d'un colorpicker
                new ColorPickerDialog(this, this, mPaint.getColor()).show();
                return true;
            case EMBOSS_MENU_ID:
                // application d'un filtre emboss sur les traits de la brosse
                if (mPaint.getMaskFilter() != mEmboss) {
                    mPaint.setMaskFilter(mEmboss);
                } else {
                    mPaint.setMaskFilter(null);
                }
                return true;
            case BLUR_MENU_ID:
                // application d'un filtre blur sur les traits de la brosse
                if (mPaint.getMaskFilter() != mBlur) {
                    mPaint.setMaskFilter(mBlur);
                } else {
                    mPaint.setMaskFilter(null);
                }
                return true;
            case ERASE_MENU_ID:
                // effacement du contenu de l'objet paint
                mPaint.setXfermode(new PorterDuffXfermode(
                                                        PorterDuff.Mode.CLEAR));
                return true;
            case SRCATOP_MENU_ID:
                mPaint.setXfermode(new PorterDuffXfermode(
                                                    PorterDuff.Mode.SRC_ATOP));
                mPaint.setAlpha(0x80);
                return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

ColorPickerDialog.java[modifier | modifier le wikicode]

package com.example.fingerpaint;

import android.os.Bundle;
import android.app.Dialog;
import android.content.Context;
import android.graphics.*;
import android.view.MotionEvent;
import android.view.View;

 public class ColorPickerDialog extends Dialog {

  public interface OnColorChangedListener {
     void colorChanged(int color);
  }

   private OnColorChangedListener mListener;
  private int mInitialColor;

   private static class ColorPickerView extends View {
  private Paint mPaint;
  private Paint mCenterPaint;
  private final int[] mColors;
  private OnColorChangedListener mListener;

  ColorPickerView(Context c, OnColorChangedListener l, int color) {
      super(c);
      mListener = l;
      mColors = new int[] {
          0xFFFF0000, 0xFFFF00FF, 0xFF0000FF, 0xFF00FFFF, 0xFF00FF00,
          0xFFFFFF00, 0xFFFF0000
      };
      Shader s = new SweepGradient(0, 0, mColors, null);

      mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
      mPaint.setShader(s);
      mPaint.setStyle(Paint.Style.STROKE);
      mPaint.setStrokeWidth(32);

      mCenterPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
      mCenterPaint.setColor(color);
      mCenterPaint.setStrokeWidth(5);
  }

  private boolean mTrackingCenter;
  private boolean mHighlightCenter;

  @Override
  protected void onDraw(Canvas canvas) {
      float r = CENTER_X - mPaint.getStrokeWidth()*0.5f;

      canvas.translate(CENTER_X, CENTER_X);

      canvas.drawOval(new RectF(-r, -r, r, r), mPaint);
      canvas.drawCircle(0, 0, CENTER_RADIUS, mCenterPaint);

      if (mTrackingCenter) {
          int c = mCenterPaint.getColor();
          mCenterPaint.setStyle(Paint.Style.STROKE);

          if (mHighlightCenter) {
              mCenterPaint.setAlpha(0xFF);
          } else {
              mCenterPaint.setAlpha(0x80);
          }
          canvas.drawCircle(0, 0,
                            CENTER_RADIUS + mCenterPaint.getStrokeWidth(),
                            mCenterPaint);

          mCenterPaint.setStyle(Paint.Style.FILL);
          mCenterPaint.setColor(c);
      }
  }

  @Override
  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
      setMeasuredDimension(CENTER_X*2, CENTER_Y*2);
  }

  private static final int CENTER_X = 100;
  private static final int CENTER_Y = 100;
  private static final int CENTER_RADIUS = 32;

  private int floatToByte(float x) {
      int n = java.lang.Math.round(x);
      return n;
  }
  private int pinToByte(int n) {
      if (n < 0) {
          n = 0;
      } else if (n > 255) {
          n = 255;
      }
      return n;
  }

  private int ave(int s, int d, float p) {
      return s + java.lang.Math.round(p * (d - s));
  }

  private int interpColor(int colors[], float unit) {
      if (unit <= 0) {
          return colors[0];
      }
      if (unit >= 1) {
          return colors[colors.length - 1];
      }

      float p = unit * (colors.length - 1);
      int i = (int)p;
      p -= i;

      // now p is just the fractional part [0...1) and i is the index
      int c0 = colors[i];
      int c1 = colors[i+1];
      int a = ave(Color.alpha(c0), Color.alpha(c1), p);
      int r = ave(Color.red(c0), Color.red(c1), p);
      int g = ave(Color.green(c0), Color.green(c1), p);
      int b = ave(Color.blue(c0), Color.blue(c1), p);

      return Color.argb(a, r, g, b);
  }

  private int rotateColor(int color, float rad) {
      float deg = rad * 180 / 3.1415927f;
      int r = Color.red(color);
      int g = Color.green(color);
      int b = Color.blue(color);

      ColorMatrix cm = new ColorMatrix();
      ColorMatrix tmp = new ColorMatrix();

      cm.setRGB2YUV();
      tmp.setRotate(0, deg);
      cm.postConcat(tmp);
      tmp.setYUV2RGB();
      cm.postConcat(tmp);

      final float[] a = cm.getArray();

      int ir = floatToByte(a[0] * r +  a[1] * g +  a[2] * b);
      int ig = floatToByte(a[5] * r +  a[6] * g +  a[7] * b);
      int ib = floatToByte(a[10] * r + a[11] * g + a[12] * b);

      return Color.argb(Color.alpha(color), pinToByte(ir),
                        pinToByte(ig), pinToByte(ib));
  }

  private static final float PI = 3.1415926f;

  @Override
  public boolean onTouchEvent(MotionEvent event) {
      float x = event.getX() - CENTER_X;
      float y = event.getY() - CENTER_Y;
      boolean inCenter = java.lang.Math.sqrt(x*x + y*y) <= CENTER_RADIUS;

      switch (event.getAction()) {
          case MotionEvent.ACTION_DOWN:
              mTrackingCenter = inCenter;
              if (inCenter) {
                  mHighlightCenter = true;
                  invalidate();
                  break;
              }
          case MotionEvent.ACTION_MOVE:
              if (mTrackingCenter) {
                  if (mHighlightCenter != inCenter) {
                      mHighlightCenter = inCenter;
                      invalidate();
                  }
              } else {
                  float angle = (float)java.lang.Math.atan2(y, x);
                  // need to turn angle [-PI ... PI] into unit [0....1]
                  float unit = angle/(2*PI);
                  if (unit < 0) {
                      unit += 1;
                  }
                  mCenterPaint.setColor(interpColor(mColors, unit));
                  invalidate();
              }
              break;
          case MotionEvent.ACTION_UP:
              if (mTrackingCenter) {
                  if (inCenter) {
                      mListener.colorChanged(mCenterPaint.getColor());
                  }
                  mTrackingCenter = false;    // so we draw w/o halo
                  invalidate();
              }
              break;
      }
      return true;
     }
   }

    public ColorPickerDialog(Context context,
                       OnColorChangedListener listener,
                       int initialColor) {
  super(context);

  mListener = listener;
  mInitialColor = initialColor;
 }

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    OnColorChangedListener l = new OnColorChangedListener() {
      public void colorChanged(int color) {
          mListener.colorChanged(color);
          dismiss();
      }
  };

  setContentView(new ColorPickerView(getContext(), l, mInitialColor));
   setTitle("Pick a Color");
 }
}