Create a simple Paint app for Android 간단한 안드로이드 그림판 만들기
Android 2019. 12. 8. 14:30 |반응형
Create a simple drawing app for Android.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 | public class MainActivity extends AppCompatActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(new MyView(this)); } public class MyView extends View { Paint paint = new Paint(); boolean isDrawing = false; ArrayList<Float> coordinateList = new ArrayList<>(100); // Each ArrayList instance has a capacity. The capacity is the size of the array used to store // the elements in the list. It is always at least as large as the list size. As elements are // added to an ArrayList, its capacity grows automatically. The details of the growth policy // are not specified beyond the fact that adding an element has constant amortized time cost. MyView(Context context) { super(context); paint.setColor(Color.BLUE); // 0xff0000ff paint.setStrokeWidth(8); } @Override public void onDraw(Canvas canvas) { // ArrayList, Float[], float[]은 서로 직접 호환되지 않음. Float[] coordinateFloat = coordinateList.toArray(new Float[coordinateList.size()]); float[] coordinate = new float[coordinateFloat.length]; for (int i = 0; i < coordinateFloat.length; i++) { coordinate[i] = coordinateFloat[i].floatValue(); } // 특정 색으로 화면을 채우는 메서드 // void drawRGB(int r, int g, int b) // void drawARGB(int a, int r, int g, int b) // void drawColor(int color) // void drawPaint(Paint paint) canvas.drawARGB(255, 255, 255, 0); // Yellow canvas.drawLines(coordinate, paint); // Draw a series of lines. Each line is taken from 4 consecutive values in the pts array. // Thus to draw 1 line, the array must contain at least 4 values. This is logically the // same as drawing the array as follows: drawLine(pts[0], pts[1], pts[2], pts[3]) followed // by drawLine(pts[4], pts[5], pts[6], pts[7]) and so on. } // drawLines()는 4개의 좌표를 이용해 1개의 직선을 그린다(x1, y1, x2, y2) // 1개의 직선을 그리고 다음 직선의 시작 좌표(x1, y1)에 이전 끝 좌표(x2, y2)가 // 없다면 끊어진 선으로 그려지게 된다. 마우스를 뗄때는 다음 직선의 시작 좌표로 // 넣어준 값 두 개(x1, y1)를 삭제 해야 한다. @Override public boolean onTouchEvent(MotionEvent event) { switch (event.getAction()) { case MotionEvent.ACTION_DOWN: coordinateList.add(event.getX()); coordinateList.add(event.getY()); isDrawing = true; break; case MotionEvent.ACTION_MOVE: if (isDrawing) // 이 코드에서는 별 의미는 없는 if { coordinateList.add(event.getX()); coordinateList.add(event.getY()); coordinateList.add(event.getX()); coordinateList.add(event.getY()); } invalidate(); break; case MotionEvent.ACTION_UP: coordinateList.remove(coordinateList.size() -1); coordinateList.remove(coordinateList.size() -1); isDrawing = false; break; default: break; } return true; } } |
Run the app and draw.
To simplify the code, you can also use Path. The result is the same.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 | public class MainActivity extends AppCompatActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(new MyView(this)); } public class MyView extends View { Paint paint = new Paint(); boolean isDrawing = false; Path path = new Path(); MyView(Context context) { super(context); paint.setColor(Color.BLUE); // 0xff0000ff paint.setStyle(Paint.Style.STROKE); // Paint.Style.FILL(기본값)로 하면 채워진 도형이 그려진다 paint.setStrokeWidth(8); } @Override public void onDraw(Canvas canvas) { canvas.drawARGB(255, 255, 255, 0); canvas.drawPath(path, paint); } @Override public boolean onTouchEvent(MotionEvent event) { switch (event.getAction()) { case MotionEvent.ACTION_DOWN: path.moveTo(event.getX(), event.getY()); isDrawing = true; break; case MotionEvent.ACTION_MOVE: if (isDrawing) { path.lineTo(event.getX(), event.getY()); invalidate(); } break; case MotionEvent.ACTION_UP: isDrawing = false; break; default: break; } return true; } } |
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