Button

Collaboration diagram for Button:

Data Structures
struct	BUTTON_STRUCT

Macros
#define	AUTO   0
	Use this value instead of x2, y2 in the BUTTON_STRUCT to autocalculate the button width/height. More...

Typedefs
typedef void(*	BUTTON_CALLBACK) (void *button)

Functions
bool	gui_button_add (BUTTON_STRUCT *button)
void	gui_button_remove (BUTTON_STRUCT *button)
void	gui_button_redraw (BUTTON_STRUCT *button)

Detailed Description

The Button Gui-Element is a clickable, rectangular box with a label inside. When it is pressed and released you will be notified via the provided callback.

Macro Definition Documentation

#define AUTO   0

Use this value instead of x2, y2 in the BUTTON_STRUCT to autocalculate the button width/height.

Definition at line 65 of file button.h.

Typedef Documentation

typedef void(* BUTTON_CALLBACK) (void *button)

Prototype for Event Listeners (called when the button is pressed)

Note

You should NOT execute long running things in this callback nor should you update the gui. But you can call gui_screen_navigate() for instance.

Parameters

button

The pointer to the BUTTON_STRUCT where to corresponding Button was pressed

Definition at line 49 of file button.h.

Function Documentation

bool gui_button_add

(

BUTTON_STRUCT *

button

)

Adds a button. Your Callback will be called from now on, if the button was pressed

Parameters

button

A Pointer to the preinitialized BUTTON_STRUCT

Returns

true on success

Definition at line 133 of file button.c.

{
    if (touch_have_empty(1)) { //Check if the touch module can handle one additional area
        //Calculate width and height of the button text
        unsigned int strwidth = tft_font_width(button->font) * strlen(button->text);
        unsigned char strheight = tft_font_height(button->font);

        button->base.hookedActions = PEN_DOWN; //At first we are interested in PEN_DOWN events
        button->base.callback = buttons_cb; //Use our own callback for the touch area events

        if (button->base.x2 == AUTO) { //The user wants us to calculate the button width automatically
            //Use string width + half of a character width as button width
            button->base.x2 = button->base.x1 - 1 + strwidth + (tft_font_width(button->font) / 2);
        } else if ((button->base.x2 - button->base.x1 + 1) < (strwidth + 2)) { //the provided width is too small to fit the entire text
            return false; //report error
        }

        if (button->base.y2 == AUTO) { //The user wants us to calculate the button height automatically
            //Use one and a half character heights as button height
            button->base.y2 = button->base.y1 - 1 + strheight + (strheight / 2);
        } else if ((button->base.y2 - button->base.y1 + 1) < (strheight + 2)) { //the provided height is too small to fit the text
            return  false;
        }

        gui_button_redraw(button); //call the redraw method, which will take care of drawing the entire button
        return touch_register_area(&button->base);  //Register the touch area and receive events for this button, from now on
    }

    return false; //no more touch areas left
}

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void gui_button_redraw

(

BUTTON_STRUCT *

button

)

Redraws the button. Call this method if you have to redraw the entire screen or if you want to draw a button on top of an image.

Parameters

button

A Pointer to the BUTTON_STRUCT

Definition at line 164 of file button.c.

{
    //Calculate text dimensions and shadow colors
    unsigned int strwidth = tft_font_width(button->font) * strlen(button->text);
    unsigned char strheight = tft_font_height(button->font);
    uint16_t c_light, c_dark;
    calculate_shadows(button->bgcolor, &c_light, &c_dark);

    //Draw the background and the 4 lines (shadow colors)
    tft_fill_rectangle(button->base.x1 + 1, button->base.y1 + 1, button->base.x2 - 1, button->base.y2 - 1, button->bgcolor);
    tft_draw_line(button->base.x1 + 1, button->base.y1, button->base.x2 - 1, button->base.y1, c_light); //North
    tft_draw_line(button->base.x1, button->base.y1 + 1, button->base.x1, button->base.y2 - 1, c_light); //West
    tft_draw_line(button->base.x1 + 1, button->base.y2, button->base.x2 - 1, button->base.y2, c_dark); //South
    tft_draw_line(button->base.x2, button->base.y1 + 1, button->base.x2, button->base.y2 - 1, c_dark); //East

    //Draw the text
    tft_print_line(button->base.x1 + (button->base.x2 - button->base.x1 + 1 - strwidth) / 2, button->base.y1 + (button->base.y2 - button->base.y1 + 1 - strheight) / 2, button->txtcolor, button->bgcolor, button->font, button->text);

}

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void gui_button_remove

(

BUTTON_STRUCT *

button

)

Removes the button. You will no longer receive events for this button. This function will not overdraw the region where the button was located.

Parameters

button

A Pointer to the BUTTON_STRUCT

Definition at line 184 of file button.c.

{
    //We only need to unregister the touch area, as we have not allocated anything else
    touch_unregister_area((TOUCH_AREA_STRUCT*)button);
}

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