colorStar.c

This example shows how to use selection lists. It presents a strange, moving list of options to select the color of the background and a normal, rectangular section list to control the movement of the first. It also adds a button to end the execution of the program.

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

#include <mgsLib.h>
#include <mrmWidgets.h>


#define SCRW    800
#define SCRH    600

#define RAD     250.0
#define SPEED   0.005

void setPos(double angle);
int setCol(int op);
int contrast(int c);

// Texts for both selection lists
char *modeText[3] = {"Rotate counterclockwise", "Stop rotation", "Rotate clockwise"};
char *colorText[6] = {"Red", "Magenta", "Blue", "Yellow", "Green", "Cyan"};
// Colors associated with teh second one
int colors[6] = {MGS_CRED, MGS_CMAGENTA, MGS_CBLUE, MGS_CYELLOW, MGS_CGREEN, MGS_CCYAN};
// And positions.
int hexa[12];

int main() {
    // Handlers for the main graphic elements
    int scr, sc, sc2, btn;
    // Options from the selections and colors
    int op, op2 = 0, oldop2 = 1, col, col2;
    // Animation variables
    double a = 0.0, v = SPEED;
    
    // Create the main screen and set the font for its texts
    scr = mgsCreateScreen(SCRW, SCRH, "MrMWidget Test", MGS_CBLACK, NULL);
    mgsSetFont(scr, 18, MGS_CWHITE, MGS_TRANSPARENT);   
    // Move the main window to a suitable place on screen
    mgsMoveScreen(scr, 300, 150);
    
    // Create the first, static selection and set its parameters
    sc = mrmSelectionInit(scr, 200, 75, 3, modeText, 1, MWG_SCUNIQUE | MWG_SCROUND | 10);
    mrmSelectionSetFont(sc, 20, 0, "Arial", MGS_BOLD);
    mrmSelectionSetFontColor(sc, 0xF06060, 0xFF1010, 0, 0);
    mrmSelectionSetPos(sc, 300, 260);
    // Create the moving selection and set only its font.
    sc2 = mrmSelectionInit(scr, 0, 0, 6, colorText, 0, MWG_SCMULTI | MWG_SCSYMBOL | 'V');
    mrmSelectionSetFont(sc2, 25, 0, "Forte", MGS_BOLD);
    // Create the exit button and set its aspect
    btn = mrmButtonInit(scr, 80, 40, NULL, "Exit", MGS_CGREY, 0x202020, MGS_CBLACK);
    mrmButtonSetFont(btn, 26, 0, "Arial", MGS_BOLD);
    mrmButtonSetFontColor(btn, 0x2020E0, MGS_CRED, 0x2020E0);
    mrmButtonSetPos(btn, SCRW - 100, SCRH - 50);
    
    // Main animation loop: stay until the user presses the button.
    while(mrmButtonGetCounter(btn) == 0) {
        
        // Calculate the vertex of a hexagon to place the options
        // rotated an angle a.
        setPos(a);
        // Assign the positions to the selection
        mrmSelectionSetOptionsPos(sc2, hexa);
        // Increase angle according to speed
        a = a + v;
        // Man widget loop. Selections values will change here
        mrmWLoop();
        // Calculate speed according to the option selected on the
        // static list. As its mode is unique, a number between 0 and 2
        // identifies the selected option. Use it to set speed.
        op = mrmSelectionGetVal(sc);
        v = (1 - op) * SPEED;
        // Read the option selected on the moving list
        op2 = mrmSelectionGetVal(sc2);
        // Calculate new aspects only if the selection has changed
        if (op2 != oldop2) {
            oldop2 = op2;
            // Calculate color for the background according to the selected option
            col = setCol(op2);
            // And a contrasted color for the text -it can be invissible if fixed!
            col2 = contrast(col);
            mrmSelectionSetFontColor(sc2, col2, col2, 0, 0);
        }       
        // Prepare to draw new frame
        mgsClearScreen(scr);
        // Two rectangles first, full screen and for the static list
        mgsRectangle(scr, 0, 0, SCRW - 1, SCRH - 1, col);
        mgsRectangle(scr, 280, 240, 530, 345, 0xB0B0B0);
        // Draw the widgets on the rectangles.
        mrmWShow();
        // And synchronize and update screen to end the animation.
        mgsWaitFrame();
        mgsUpdateScreen(scr);
    }
    
    // Good bye.
    exit(EXIT_SUCCESS);
}

// This funcion just calculates the coordinates of the 6 vertex of
// an hexagon of radius RAD, rotated an angle a
void setPos(double angle)
{
    int i; 
    
    for (i = 0; i < 6; i++) {
        hexa[2 * i] = SCRW / 2 - 50 + RAD * cos(angle + i * 2.0 * M_PI / 6.0); //x
        hexa[2 * i + 1] = SCRH / 2 - RAD * sin(angle + i * 2.0 * M_PI / 6.0); // y
    }
}

// Calculates the background color by adding the selected colors, dividing by 2 
// each component -than can only be 0 or FF- and saturating the resulting value
// to a byte size.
// As op comes from a multiple selection, it is a bitmap with the order of the bit
// indexing the option and its value meaning selected or not.
int setCol(int op)
{
    int i, msc = 1, resR = 0, resG = 0, resB = 0;
    for (i = 0; i < 6; i++) {
        if (op & msc) {
            resR += colors[i] & 0x7F;
            resG += (colors[i] >> 8) & 0x7F;
            resB += (colors[i] >> 16) & 0x7F;
        }
        msc = msc << 1;
    }
    
    resR = resR & 0xFF;
    resG = resG & 0xFF;
    resB = resB & 0xFF;
    
    return mgsRGBColor(resR, resG, resB);
}

// Add 80 and saturate each component to get a contrasted color and avoid
// the text disappearing due to changes on the background color.
int contrast(int c)
{
    int r, g, b;
    
    r = ((c & 0xFF) + 0x80) & 0xFF;
    g = (((c >> 8)& 0xFF) + 0x80) & 0xFF;
    b = (((c >> 16)& 0xFF) + 0x80) & 0xFF;
    
    return mgsRGBColor(r, g, b);
}