Difference between revisions of "PushButton"
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Latest revision as of 13:51, 9 September 2024
A push button is a stand-alone widget with a static size and a text where the text is drawn centered inside the button area. A push button can have the state pressed or unpressed.
API Reference
The API reference for the push button widget can be found here.
Custom Draw Routines
The button widget predefines a number of custom draw routines. They can be set using gwinSetCustomDraw()
or by specifying the custom draw routine in the GWidgetInit structure during creation. Some require certain features to be turned on in your gfxconf.h file. The predefined custom draw routines are:
Custom Draw Routine | Requires | Description |
---|---|---|
gwinButtonDraw_Normal | The standard button look | |
gwinButtonDraw_Rounded | GDISP_NEED_ARC | A button with rounded corners |
gwinButtonDraw_Ellipse | GDISP_NEED_ELLIPSE | An elliptical button |
gwinButtonDraw_ArrowUp | GDISP_NEED_CONVEX_POLYGON | An up arrow |
gwinButtonDraw_ArrowDown | GDISP_NEED_CONVEX_POLYGON | An down arrow |
gwinButtonDraw_ArrowLeft | GDISP_NEED_CONVEX_POLYGON | An left arrow |
gwinButtonDraw_ArrowRight | GDISP_NEED_CONVEX_POLYGON | An right arrow |
gwinButtonDraw_Image | GDISP_NEED_IMAGE | An image button. The param must be a gdispImage pointer. See the API documentation for details. |
Cancel feature
The button implementation allows it to cancel a button pressed event: When you push a button but release it outside of it's area, the action is canceled. However, this feature can become a problem with touchscreen systems which have a lot of noise on the output coordinates. When you have a small button, the chance that just one point is outside of the area of a small button is very high.
To fix this issue, there's the macro GWIN_BUTTON_LAZY_RELEASE
available. When you set it to TRUE in your gfxconf.h, the cancel feature get's disabled.
Of course the real solution is to fix the noise. One of the things that may help is reducing your SPI frequency if your touch is connected via SPI. There is a demo program that allows you to fine-tune the parameters for your touch driver in tools/ginput_touch_driver_test. Compile and run it and each step will help you adjust one of the touch parameters. Unfortunately the parameters are not run-time changable. You need to run a test, alter the paremter, recompile and then run it again. Also don't try to do all the parameters at the same time as the setting of one can affect the setting of others - so do the tests one step at a time.
Example
The following example shows how to use a push button widget:
#include "gfx.h" static GListener gl; static GHandle ghButton1; static void createWidgets(void) { GWidgetInit wi; // Apply some default values for GWIN gwinWidgetClearInit(&wi); wi.g.show = TRUE; // Apply the button parameters wi.g.width = 100; wi.g.height = 30; wi.g.y = 10; wi.g.x = 10; wi.text = "Push Button"; // Create the actual button ghButton1 = gwinButtonCreate(NULL, &wi); } int main(void) { GEvent* pe; // Initialize the display gfxInit(); // Set the widget defaults gwinSetDefaultFont(gdispOpenFont("UI2")); gwinSetDefaultStyle(&WhiteWidgetStyle, FALSE); gdispClear(White); // create the widget createWidgets(); // We want to listen for widget events geventListenerInit(&gl); gwinAttachListener(&gl); while(1) { // Get an Event pe = geventEventWait(&gl, TIME_INFINITE); switch(pe->type) { case GEVENT_GWIN_BUTTON: if (((GEventGWinButton*)pe)->gwin == ghButton1) { // Our button has been pressed printf("Button clicked\r\n"); } break; default: break; } } return 0; }