#ENDLESS CANVAS DRAWING PROGRAM HOW TO#
#ENDLESS CANVAS DRAWING PROGRAM UPDATE#
#ENDLESS CANVAS DRAWING PROGRAM ANDROID#
#ENDLESS CANVAS DRAWING PROGRAM CODE#

#ENDLESS CANVAS DRAWING PROGRAM CODE#

Update() and Draw(Canvas canvas) methodsĬopy Code public static float CannonRotationByTouch( int touch_x, int touch_y, Cannon cannon) This object is responsible for all game business logic, it keeps the instances of all displayed objects (in our case: Bubbles, Aim and the Cannon). *I didn’t include that solution in our DisplayThread implementation because I wanted to keep it simple. This problem can be solved by taking timestamp at the beginning of the loop and subtracting it from the sleep time, which will make our each loop execution time the same. That makes our game rendering not smooth, since loop execution time is different from one another.

#ENDLESS CANVAS DRAWING PROGRAM UPDATE#

We need to be aware of the fact that the time that it takes to render and update the game is not consistent.įor example, if you have one bubble to advance, it wouldn’t take the same time as to advance 550 bubbles on the screen. In our implementation we are calling Thread.sleep() with a hardcoded value, expecting it to stop for a while and then continue the logic execution. Our brain process about 20 frames per second, our code refreshes the screen every 45 millisecond, which makes it 22 fps. That will display our objects with updated parameters on our display.įinally it unlocks the canvas, and goes to sleep for a specified amount of time, that calls fps (frames per second). Next it locks the canvas (from our SurficeView class), paints the whole view with the black background and passes the canvas to GameEngine Draw() method. That will update our business logic (in our case advance the balloons). SetIsRunning(boolean state) is called only from SurfaceHolder.Callback interface methods that implemented in our GameView class.įirst thing that run() method does as it enters the while loop, is to call the Update() method in the GameEngine object. Run() method will loop in its while loop as long as the boolean _ isOnRun variable is not set to false, which happens only by invoking the SetIsRunning(boolean state) method. _surfaceHolder.unlockCanvasAndPost(canvas) Clears the screen with black paint and draws // object on the canvas synchronized (_surfaceHolder)Ĭanvas.getWidth(),canvas.getHeight(), _backgroundPaint) Updates the game objects buisiness logicĬanvas canvas = _surfaceHolder.lockCanvas(null) Looping until the boolean is false while (_isOnRun) Our GameView implements SurfaceHolder.Callback interface: When created (when called new in our GameActvity), GameView initializes and starts the DisplayThread object. This class implements the logic for our display. GameView class extends SurficeView that extends View class, that’s why we could set it as our activity content view. That will change our business logic and create an interaction between the user and our application. They call appropriate methods in our GameEngine object. These methods are invoked as a user touches the screen of our activity. SetLastTouch(event.getX(), event.getY()) * activates on touch down event*/ private void OnActionDown(MotionEvent event) * activates on touch up event*/ private void OnActionUp(MotionEvent event)ĪppConstants. GetEngine().SetLastTouch(event.getX(), event.getY()) GetEngine().SetCannonRotaion(x, y) ĪppConstants.

Let’s examine our GameActivity onCreate() method:Ĭopy Code /* activates on touch move event*/ private void OnActionMove(MotionEvent event)ĪppConstants. We are going to create an activity that will listen to touch events (user inputs) and set its content view as custom view that we will implement afterwards. Objects that constantly move, such as bubbles, keep their deltas which identify their direction. In our game we have 3 objects of that type: Cannon, Bubble and Aim.Įvery object has its x and y coordinates that identifies its location on the screen.

#ENDLESS CANVAS DRAWING PROGRAM ANDROID#

Program modules communication diagramĮach figure that is displayed on the screen of our Android device is a java object with its own logic. Store that data somewhere in our program.ģ. We need to establish several modules in our program:Ģ. We are going to implement the fundamental stage of a 2D bubble game, which includes a cannon shooting bubbles to our touches direction. We will examine the basic concepts and create a display interaction by touch events.

#ENDLESS CANVAS DRAWING PROGRAM HOW TO#

This article will explain how to create a simple game on Android platform using SurfaceView class only by managed Java code.

Update() and Draw(Canvas canvas) methods.

Endless canvas drawing program