keyboard.c
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/*
* keyboard.c
* written by Holmes Futrell
* use however you want
*/
#import "SDL.h"
#import "common.h"
#define GLYPH_SIZE_IMAGE 16 /* size of glyphs (characters) in the bitmap font file */
#define GLYPH_SIZE_SCREEN 32 /* size of glyphs (characters) as shown on the screen */
static SDL_Texture *texture; /* texture where we'll hold our font */
/* function declarations */
void cleanup(void);
void drawBlank(int x, int y);
static SDL_Renderer *renderer;
static int numChars = 0; /* number of characters we've typed so far */
static SDL_bool lastCharWasColon = 0; /* we use this to detect sequences such as :) */
static SDL_Color bg_color = { 50, 50, 100, 255 }; /* color of background */
/* this structure maps a scancode to an index in our bitmap font.
it also contains data about under which modifiers the mapping is valid
(for example, we don't want shift + 1 to produce the character '1',
but rather the character '!')
*/
typedef struct
{
SDL_Scancode scancode; /* scancode of the key we want to map */
int allow_no_mod; /* is the map valid if the key has no modifiers? */
SDL_Keymod mod; /* what modifiers are allowed for the mapping */
int index; /* what index in the font does the scancode map to */
} fontMapping;
#define TABLE_SIZE 51 /* size of our table which maps keys and modifiers to font indices */
/* Below is the table that defines the mapping between scancodes and modifiers to indices in the
bitmap font. As an example, then line '{ SDL_SCANCODE_A, 1, KMOD_SHIFT, 33 }' means, map
the key A (which has scancode SDL_SCANCODE_A) to index 33 in the font (which is a picture of an A),
The '1' means that the mapping is valid even if there are no modifiers, and KMOD_SHIFT means the
mapping is also valid if the user is holding shift.
*/
fontMapping map[TABLE_SIZE] = {
{SDL_SCANCODE_A, 1, KMOD_SHIFT, 33}, /* A */
{SDL_SCANCODE_B, 1, KMOD_SHIFT, 34}, /* B */
{SDL_SCANCODE_C, 1, KMOD_SHIFT, 35}, /* C */
{SDL_SCANCODE_D, 1, KMOD_SHIFT, 36}, /* D */
{SDL_SCANCODE_E, 1, KMOD_SHIFT, 37}, /* E */
{SDL_SCANCODE_F, 1, KMOD_SHIFT, 38}, /* F */
{SDL_SCANCODE_G, 1, KMOD_SHIFT, 39}, /* G */
{SDL_SCANCODE_H, 1, KMOD_SHIFT, 40}, /* H */
{SDL_SCANCODE_I, 1, KMOD_SHIFT, 41}, /* I */
{SDL_SCANCODE_J, 1, KMOD_SHIFT, 42}, /* J */
{SDL_SCANCODE_K, 1, KMOD_SHIFT, 43}, /* K */
{SDL_SCANCODE_L, 1, KMOD_SHIFT, 44}, /* L */
{SDL_SCANCODE_M, 1, KMOD_SHIFT, 45}, /* M */
{SDL_SCANCODE_N, 1, KMOD_SHIFT, 46}, /* N */
{SDL_SCANCODE_O, 1, KMOD_SHIFT, 47}, /* O */
{SDL_SCANCODE_P, 1, KMOD_SHIFT, 48}, /* P */
{SDL_SCANCODE_Q, 1, KMOD_SHIFT, 49}, /* Q */
{SDL_SCANCODE_R, 1, KMOD_SHIFT, 50}, /* R */
{SDL_SCANCODE_S, 1, KMOD_SHIFT, 51}, /* S */
{SDL_SCANCODE_T, 1, KMOD_SHIFT, 52}, /* T */
{SDL_SCANCODE_U, 1, KMOD_SHIFT, 53}, /* U */
{SDL_SCANCODE_V, 1, KMOD_SHIFT, 54}, /* V */
{SDL_SCANCODE_W, 1, KMOD_SHIFT, 55}, /* W */
{SDL_SCANCODE_X, 1, KMOD_SHIFT, 56}, /* X */
{SDL_SCANCODE_Y, 1, KMOD_SHIFT, 57}, /* Y */
{SDL_SCANCODE_Z, 1, KMOD_SHIFT, 58}, /* Z */
{SDL_SCANCODE_0, 1, 0, 16}, /* 0 */
{SDL_SCANCODE_1, 1, 0, 17}, /* 1 */
{SDL_SCANCODE_2, 1, 0, 18}, /* 2 */
{SDL_SCANCODE_3, 1, 0, 19}, /* 3 */
{SDL_SCANCODE_4, 1, 0, 20}, /* 4 */
{SDL_SCANCODE_5, 1, 0, 21}, /* 5 */
{SDL_SCANCODE_6, 1, 0, 22}, /* 6 */
{SDL_SCANCODE_7, 1, 0, 23}, /* 7 */
{SDL_SCANCODE_8, 1, 0, 24}, /* 8 */
{SDL_SCANCODE_9, 1, 0, 25}, /* 9 */
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{SDL_SCANCODE_SPACE, 1, 0, 0}, /* ' ' */
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{SDL_SCANCODE_1, 0, KMOD_SHIFT, 1}, /* ! */
{SDL_SCANCODE_SLASH, 0, KMOD_SHIFT, 31}, /* ? */
{SDL_SCANCODE_SLASH, 1, 0, 15}, /* / */
{SDL_SCANCODE_COMMA, 1, 0, 12}, /* , */
{SDL_SCANCODE_SEMICOLON, 1, 0, 27}, /* ; */
{SDL_SCANCODE_SEMICOLON, 0, KMOD_SHIFT, 26}, /* : */
{SDL_SCANCODE_PERIOD, 1, 0, 14}, /* . */
{SDL_SCANCODE_MINUS, 1, 0, 13}, /* - */
{SDL_SCANCODE_EQUALS, 0, KMOD_SHIFT, 11}, /* = */
{SDL_SCANCODE_APOSTROPHE, 1, 0, 7}, /* ' */
{SDL_SCANCODE_APOSTROPHE, 0, KMOD_SHIFT, 2}, /* " */
{SDL_SCANCODE_5, 0, KMOD_SHIFT, 5}, /* % */
};
/*
This function maps an SDL_KeySym to an index in the bitmap font.
It does so by scanning through the font mapping table one entry
at a time.
If a match is found (scancode and allowed modifiers), the proper
index is returned.
If there is no entry for the key, -1 is returned
*/
int
keyToIndex(SDL_Keysym key)
{
int i, index = -1;
for (i = 0; i < TABLE_SIZE; i++) {
fontMapping compare = map[i];
if (key.scancode == compare.scancode) {
/* if this entry is valid with no key mod and we have no keymod, or if
the key's modifiers are allowed modifiers for that mapping */
if ((compare.allow_no_mod && key.mod == 0)
|| (key.mod & compare.mod)) {
index = compare.index;
break;
}
}
}
return index;
}
/*
This function returns and x,y position for a given character number.
It is used for positioning each character of text
*/
void
getPositionForCharNumber(int n, int *x, int *y)
{
int x_padding = 16; /* padding space on left and right side of screen */
int y_padding = 32; /* padding space at top of screen */
/* figure out the number of characters that can fit horizontally across the screen */
int max_x_chars = (SCREEN_WIDTH - 2 * x_padding) / GLYPH_SIZE_SCREEN;
int line_separation = 5; /* pixels between each line */
*x = (n % max_x_chars) * GLYPH_SIZE_SCREEN + x_padding;
*y = (n / max_x_chars) * (GLYPH_SIZE_SCREEN + line_separation) +
y_padding;
}
void
drawIndex(int index)
{
int x, y;
getPositionForCharNumber(numChars, &x, &y);
SDL_Rect srcRect =
{ GLYPH_SIZE_IMAGE * index, 0, GLYPH_SIZE_IMAGE, GLYPH_SIZE_IMAGE };
SDL_Rect dstRect = { x, y, GLYPH_SIZE_SCREEN, GLYPH_SIZE_SCREEN };
drawBlank(x, y);
SDL_RenderCopy(renderer, texture, &srcRect, &dstRect);
}
/* draws the cursor icon at the current end position of the text */
void
drawCursor(void)
{
drawIndex(29); /* cursor is at index 29 in the bitmap font */
}
/* paints over a glyph sized region with the background color
in effect it erases the area
*/
void
drawBlank(int x, int y)
{
SDL_Rect rect = { x, y, GLYPH_SIZE_SCREEN, GLYPH_SIZE_SCREEN };
SDL_SetRenderDrawColor(renderer, bg_color.r, bg_color.g, bg_color.b, bg_color.a);
SDL_RenderFillRect(renderer, &rect);
}
/* moves backwards one character, erasing the last one put down */
void
backspace(void)
{
int x, y;
if (numChars > 0) {
getPositionForCharNumber(numChars, &x, &y);
drawBlank(x, y);
numChars--;
getPositionForCharNumber(numChars, &x, &y);
drawBlank(x, y);
drawCursor();
}
}
/* this function loads our font into an SDL_Texture and returns the SDL_Texture */
SDL_Texture*
loadFont(void)
{
SDL_Surface *surface = SDL_LoadBMP("kromasky_16x16.bmp");
if (!surface) {
printf("Error loading bitmap: %s\n", SDL_GetError());
return 0;
} else {
/* set the transparent color for the bitmap font (hot pink) */
SDL_SetColorKey(surface, 1, SDL_MapRGB(surface->format, 238, 0, 252));
/* now we convert the surface to our desired pixel format */
int format = SDL_PIXELFORMAT_ABGR8888; /* desired texture format */
Uint32 Rmask, Gmask, Bmask, Amask; /* masks for desired format */
int bpp; /* bits per pixel for desired format */
SDL_PixelFormatEnumToMasks(format, &bpp, &Rmask, &Gmask, &Bmask,
&Amask);
SDL_Surface *converted =
SDL_CreateRGBSurface(0, surface->w, surface->h, bpp, Rmask, Gmask,
Bmask, Amask);
SDL_BlitSurface(surface, NULL, converted, NULL);
/* create our texture */
texture =
SDL_CreateTextureFromSurface(renderer, converted);
if (texture == 0) {
printf("texture creation failed: %s\n", SDL_GetError());
} else {
/* set blend mode for our texture */
SDL_SetTextureBlendMode(texture, SDL_BLENDMODE_BLEND);
}
SDL_FreeSurface(surface);
SDL_FreeSurface(converted);
return texture;
}
}
int
main(int argc, char *argv[])
{
int index; /* index of last key we pushed in the bitmap font */
SDL_Window *window;
SDL_Event event; /* last event received */
SDL_Keymod mod; /* key modifiers of last key we pushed */
SDL_Scancode scancode; /* scancode of last key we pushed */
if (SDL_Init(SDL_INIT_VIDEO) < 0) {
printf("Error initializing SDL: %s", SDL_GetError());
}
/* create window */
window = SDL_CreateWindow("iPhone keyboard test", 0, 0, SCREEN_WIDTH, SCREEN_HEIGHT, 0);
/* create renderer */
renderer = SDL_CreateRenderer(window, -1, 0);
/* load up our font */
loadFont();
/* draw the background, we'll just paint over it */
SDL_SetRenderDrawColor(renderer, bg_color.r, bg_color.g, bg_color.b, bg_color.a);
SDL_RenderFillRect(renderer, NULL);
SDL_RenderPresent(renderer);
int done = 0;
/* loop till we get SDL_Quit */
while (SDL_WaitEvent(&event)) {
switch (event.type) {
case SDL_QUIT:
done = 1;
break;
case SDL_KEYDOWN:
index = keyToIndex(event.key.keysym);
scancode = event.key.keysym.scancode;
mod = event.key.keysym.mod;
if (scancode == SDL_SCANCODE_DELETE) {
/* if user hit delete, delete the last character */
backspace();
lastCharWasColon = 0;
} else if (lastCharWasColon && scancode == SDL_SCANCODE_0
&& (mod & KMOD_SHIFT)) {
/* if our last key was a colon and this one is a close paren, the make a hoppy face */
backspace();
drawIndex(32); /* index for happy face */
numChars++;
drawCursor();
lastCharWasColon = 0;
} else if (index != -1) {
/* if we aren't doing a happy face, then just draw the normal character */
drawIndex(index);
numChars++;
drawCursor();
lastCharWasColon =
(event.key.keysym.scancode == SDL_SCANCODE_SEMICOLON
&& (event.key.keysym.mod & KMOD_SHIFT));
}
/* check if the key was a colon */
/* draw our updates to the screen */
SDL_RenderPresent(renderer);
break;
case SDL_MOUSEBUTTONUP:
/* mouse up toggles onscreen keyboard visibility */
if (SDL_IsTextInputActive()) {
SDL_StopTextInput();
} else {
SDL_StartTextInput();
}
break;
}
}
cleanup();
return 0;
}
/* clean up after ourselves like a good kiddy */
void
cleanup(void)
{
SDL_DestroyTexture(texture);
SDL_Quit();
}