Project 3 - Logic, Steps

Drawing Application Logic -

Initial Logic

For Project 3, you will create a simple drawing application where 4 buttons allow you to choose which pattern to draw. One additional button will clear the drawing canvas. 3 Sliders will be used to change the hue, saturation, brightness of the pattern that's drawn.

The code on this page, and the image below shows a first iteration for this project

Overall Project Logic - Including Slider Logic

Button[ ] and ButtonGroup

  • Create an array of 4 Buttons that function as a ButtonGroup to control which pattern is drawn.

  • Create 4 simple patterns (PShapes) that can be drawn at the mouse position, the active pattern can be changed by selecting one of 4 pattern buttons.

  • Add logic to have 1 of the 4 pattern buttons work as an eraser ( draw an ellipse with background color, the eraser color should not be modified by the sliders)

Individual Button to Clear Canvas

  • Create an additional 5th Button that will clear the canvas, but is not part of the ButtonGroup buttons.

Pattern Objects to draw patterns

  • Create 4 Pattern Object instances.

CheckSliders( ) must occur before drawPattern( )

  • CheckSlider( ) method, checks each slider to see if it's value has changed. Also includes logic for color dependency between sliders:

    • satSlider's hue is set by the hueSlider's sliderVal;

    • brightSlider's hue is set by the hueSlider's sliderVal;

    • brightSlider's sat is set by the satSlider's sliderVal;

DrawPattern( ) Switch-case Control Structure

Switch-case structure allows one pattern to be set as active by using the activeBtnIndex of the ButtonGroup, to set an active pattern to be drawn on the canvas.

Sliders set fillColor for Patterns in drawPattern( )

before displaying the currentPattern, we'll use custom sliders to set the hue, saturation, brightness of the drawn patterns. This logic will be near the bottom of drawPattern(), just before displaying the currentPattern. See code details below below:

Main Tab Logic:

  • Use Functions to organize main-tab Logic

  • Use Classes to structure project logic.

Detailed Project Logic:

Declare Global Variables in Main Tab

//Global Variables

Pattern eraserPattern, pattern1, pattern2, pattern3; 

color bkgColor;   //declare global variable
Button myClearBtn; ///simple Button for Clear
ButtonGroup buttonGroup; 

Slider hueSlider, satSlider, brightSlider;

Logic In Main Tab: setup( )

  • Set Canvas Size: min: 800 x 600

  • Set colorMode - HSB

  • Initialize objects by calling constructors:

    • declare an Array of Buttons

      Button[] buttons;

    • initialize Array of Buttons

      buttons = new Button[4];

    • initialize each Array element by calling Button , PImageButton Constructors You need to figure out Button constructor parameter values so that buttons are positioned in a vertical stack.

      color onColor = color(300);  //set custom button colors
color offColor = color(100);
buttons[0] = new Button( 20, 20, 100, 100, onColor, offColor,"Eraser" );

//similar parameters for other buttons
buttons[1] = new PImageButton( parameters ); 
buttons[2] = new PImageButton( parameters ); 
buttons[3] = new PImageButton( parameters );

    • initialize buttonGroup by calling ButtonGroup Constructor and pass buttonArray as a parameter

      buttonGroup = new ButtonGroup( buttons);

    • initialize clearButton by calling Button Constructor - use either Button or PImageButton

      clearButton = new Button( parameters );

    • initialize Pattern Objects

      • Create 4 PShapes, pass one to each Pattern Constructor

        • Example initialization for 2 Patterns shown below

        • 4 pattern objects required

        PShape EraserPShape = createShape( ELLIPSE, 0,0,30,30);
        EraserPattern = new Pattern( EraserPShape);

        PShape shape1 = createShape( RECT, 0,0,30, 80);
        Pattern1 = new Pattern( shape1 );

  • Initialize Sliders Initialize Sliders by calling constructors with proper input parameters to determine position, size, min, max range

    hueSlider = new HueSlider( 40, height-100, 200, 50, 0, 360 );
satSlider = new SatSlider( parameters );
brightSlider = new BrightSlider(  parameters );

Logic In draw( ):

  • if mousePressed

    • checkSliders( ); //check before drawPattern, when mousePressed

    • translate(mouseX, mouseY);

    • drawPattern( );

    • resetMatrix();

  • drawButtonMenu( ) //always draw menu of Buttons

Logic in drawPattern( ):

  • connects buttons to determine currentPattern

  • sets fill for currentPattern using slider's sliderVal

  • eraserPattern color is not changed by sliders, should have fillColor, strokeColor set to global bkgColor;

  • use switch-case structure

  • switch: check which buttonGroup button is active

    void drawPattern( ){

   Pattern currentPatttern = eraserPattern;

   switch(buttonGroup.activeBtnIndex){
      case 0: 
           currentPattern.setFill(bkgColor);
           currentPattern.setStroke(bkgColor);
           currentPatttern = eraserPattern;
      break;

      case 1:
           currentPatttern = pattern1;
      break;

      case 2:
           currentPatttern = pattern2;
      break;

      case 3:
           currentPatttern = pattern3;
      break;

      default:
            println("no match");
       }//end switch-case
      if( currentPattern != eraserPattern){
          //set color using sliders sliderVal if not the eraserPattern
        float hue = hueSlider.sliderVal;
        float sat = satSlider.sliderVal;
        float bright = brightSlider.sliderVal;
        color currentColor = color( hue, sat, bright);
        currentPattern.setFill(currentColor);
      }
      currentPattern.display();

  } // end drawPattern();

Logic in drawButtonMenu( ):

Draw 5 buttons: 4 buttons in buttonGroup, 1 clearButton

  • draw a menu-background (rectangle)

  • buttonGroup.display();

  • clearButton.display();

    Logic In MouseClicked( ):

  • buttonGroup.clicked( parameters )

  • clearButton.click( parameters )

  • if clearButton is selected

    • clearCanvas( ) - draw rectangle over the canvas surface

    • reset the clearButton

    Detailed Logic for Adding Sliders to Drawing Application

In this project, sliders will be used to control Hue, Saturation, Brightness of the patterns drawn.

The sliders must be checked each time the draw-loop executes if the mousePressed, to see if the sliderVal has changed.

Sliders must always be checked for changes in sliderVal before drawing any patterns.

checkSliders( ) is a custom function in the main tab, that contains logic for checking each slider.

  • Declare global variables:

    Slider hueSlider, satSlider, brightSlider;

  • Initialize 3 Sliders in setup( ) by calling child class constructors: example

    hueSlider = new HueSlider( 40, height-100, 200, 50, 0, 360 );

  • Incorporate Sliders into project using custom functions:

    • void checkSliders( );

    • void drawSliders ( );

    • in drawPattern( ) - set currentPattern fillColor using sliderVal right before currentPattern is displayed: currentPattern.display()

      • see drawPattern above for integration of this example code:

    //Code chunk from drawPattern( ) in main tab
    if( currentPattern != eraserPattern){
    //set color using sliders sliderVal if not the eraserPattern
    float hue = hueSlider.sliderVal;
    float sat = satSlider.sliderVal;
    float bright = brightSlider.sliderVal;
    color currentColor = color( hue, sat, bright);
    currentPattern.setFill(currentColor);
    }

Logic in DrawSliders( )

This code is similar to DrawButtons, we simply want to draw a rectangle behind the sliders, and then have each slider display itself by calling the over-ridden display( ) method.

void drawSliders( ){
  //draw background rectangle behind sliders
  //display hueSlider, example:
  hueSlider.display();
  //display other sliders

}

Logic in CheckSliders( )

In CheckSliders, we must check to see if each slider has been pressed. We need to set the hue value for the satSlider using the current sliderVal of the hueSlider since the display of satSlider should change when the hueSlider is changed. Similarly for the brightSlider, it must have it's hue and sat reset to reflect current hueSlider and satSlider values.

void checkSliders(){
  ///update sliders if the mouse has been pressed within their hitbox
  hueSlider.checkPressed( mouseX, mouseY);
  satSlider.hue = hueSlider.sliderVal;
  satSlider.checkPressed( mouseX, mouseY);
  brightSlider.hue = hueSlider.sliderVal;
  brightSlider.sat = satSlider.sliderVal;
  brightSlider.checkPressed( mouseX, mouseY);
}

Additional Logic

clearButton

The clearButton is a regular button that is used to clear the canvas. The clearButton must be declared as a global object-reference variable. The clearButton behaves like a door-bell, meaning it never displays that it is in the selected state. When the clearButton is clicked, it clears the canvas, then the reset( ) method is called to turn the button off.

//global variable
Button clearButton;

Initialize in setup() The clearButton is not part of the buttonGroup buttons, but it's parameters should be defined so that the button is displayed below the other buttons that are part of the buttonGroup. `

//in setup()
clearButton = new Button(  parameters );

Add code in displayButtons( ), to display the clearButton

void displayButtons(){
//draw background rectangle
buttonGroup.display();
clearButton.display();
}

Add code in mouseClicked( ) Add code to check if the clearButton has been clicked. Then, check to see if the clearButton is currently selected, if it is, then call custom function: clearCanvas( ), then turn-off the clearButton by calling the reset( ) method.

void mouseClicked(){
  buttonGroup.clicked( mouseX, mouseY);
  clearButton.clicked( mouseX, mouseY); //check to see if it's been clicked
  if( clearButton.selected){
    //do something
    clearCanvas();
    clearButton.reset(); //turn the button  off
  }
}

Logic in clearCanvas( ):

called when clearBtn has been clicked and has on==true

  • set fill to global background color: bkgColor

  • draw a rectangle, the size of the entire canvas, to clear the canvas. rect( 0, 0, width, height)

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