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https://github.com/wesnoth/wesnoth
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Add a way to draw a circle on a canvas.
This commit is contained in:
Mark de Wever
parent
238ceb79d2
commit
b1324887fd
@ -96,6 +96,7 @@ static void put_pixel(
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* Draws a line.
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*
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* @pre @p x2 >= @p x1
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* @pre @p canvas is locked.
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*
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* @param canvas The canvas to draw upon, the caller should lock the
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* surface before calling.
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@ -179,6 +180,72 @@ static void draw_line(
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}
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}
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/**
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* Draws a circle.
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*
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* @pre The circle must fit on the canvas.
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* @pre @p canvas is locked.
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*
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* @param canvas The canvas to draw upon, the caller should lock the
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* surface before calling.
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* @param color The color of the circle to draw.
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* @param x_centre The x coordinate of the centre of the circle to draw.
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* @param y_centre The y coordinate of the centre of the circle to draw.
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* @param radius The radius of the circle to draw.
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*/
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static void draw_circle(
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surface& canvas
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, Uint32 color
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, const unsigned x_centre
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, const unsigned y_centre
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, const unsigned radius)
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{
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color = SDL_MapRGBA(canvas->format,
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((color & 0xFF000000) >> 24),
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((color & 0x00FF0000) >> 16),
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((color & 0x0000FF00) >> 8),
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((color & 0x000000FF)));
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ptrdiff_t start = reinterpret_cast<ptrdiff_t>(canvas->pixels);
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unsigned w = canvas->w;
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DBG_GUI_D << "Shape: draw circle at "
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<< x_centre << ',' << y_centre
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<< " with radius " << radius
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<< " canvas width " << w << " canvas height "
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<< canvas->h << ".\n";
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assert(static_cast<int>(x_centre + radius) < canvas->w);
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assert(static_cast<int>(x_centre - radius) >= 0);
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assert(static_cast<int>(y_centre + radius) < canvas->h);
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assert(static_cast<int>(y_centre - radius) >= 0);
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// Algorithm based on
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// http://de.wikipedia.org/wiki/Rasterung_von_Kreisen#Methode_von_Horn
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// version of 2011.02.07.
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int d = -radius;
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int x = radius;
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int y = 0;
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while(!(y > x)) {
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put_pixel(start, color, w, x_centre + x, y_centre + y);
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put_pixel(start, color, w, x_centre + x, y_centre - y);
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put_pixel(start, color, w, x_centre - x, y_centre + y);
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put_pixel(start, color, w, x_centre - x, y_centre - y);
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put_pixel(start, color, w, x_centre + y, y_centre + x);
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put_pixel(start, color, w, x_centre + y, y_centre - x);
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put_pixel(start, color, w, x_centre - y, y_centre + x);
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put_pixel(start, color, w, x_centre - y, y_centre - x);
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d += 2 * y + 1;
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++y;
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if(d > 0) {
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d -= 2 * x + 2;
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--x;
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}
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}
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}
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/***** ***** ***** ***** ***** LINE ***** ***** ***** ***** *****/
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/** Definition of a line shape. */
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@ -674,6 +741,119 @@ void trectangle::draw(surface& canvas
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}
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}
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/***** ***** ***** ***** ***** CIRCLE ***** ***** ***** ***** *****/
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/** Definition of a circle shape. */
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class tcircle
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: public tcanvas::tshape
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{
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public:
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/**
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* Constructor.
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*
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* @param cfg The config object to define the circle see
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* http://www.wesnoth.org/wiki/GUICanvasWML#Circle
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* for more info.
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*/
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explicit tcircle(const config& cfg);
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/** Implement shape::draw(). */
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void draw(surface& canvas
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, const game_logic::map_formula_callable& variables);
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private:
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tformula<unsigned>
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x_, /**< The centre x coordinate of the circle. */
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y_, /**< The centre y coordinate of the circle. */
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radius_; /**< The radius of the circle. */
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/** The color of the circle. */
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Uint32 color_;
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};
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tcircle::tcircle(const config& cfg)
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: x_(cfg["x"])
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, y_(cfg["y"])
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, radius_(cfg["radius"])
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, color_(decode_color(cfg["color"]))
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{
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/*WIKI
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* @page = GUICanvasWML
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*
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* == Circle ==
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* Definition of a circle. When drawing a circle it doesn't get blended on
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* the surface but replaces the pixels instead. A blitting flag might be
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* added later if needed.
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*
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* Keys:
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* @begin{table}{config}
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* x & f_unsigned & 0 & The x coordinate of the centre. $
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* y & f_unsigned & 0 & The y coordinate of the centre. $
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* radius & f_unsigned & 0 & The radius of the circle if 0 nothing is
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* drawn. $
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* debug & string & "" & Debug message to show upon creation$ this
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* message is not stored. $
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* @end{table}
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*
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* Variables:
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* See [[#general_variables|Line]].
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*
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* Drawing outside the area will result in unpredictable results including
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* crashing. (That should be fixed, when encountered.)
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*/
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const std::string& debug = (cfg["debug"]);
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if(!debug.empty()) {
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DBG_GUI_P << "Circle: found debug message '" << debug << "'.\n";
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}
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}
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void tcircle::draw(surface& canvas
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, const game_logic::map_formula_callable& variables)
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{
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/**
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* @todo formulas are now recalculated every draw cycle which is a bit
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* silly unless there has been a resize. So to optimize we should use an
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* extra flag or do the calculation in a separate routine.
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*/
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const unsigned x = x_(variables);
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const unsigned y = y_(variables);
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const unsigned radius = radius_(variables);
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DBG_GUI_D << "Circle: drawn at "
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<< x << ',' << y << " radius " << radius
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<< " canvas size " << canvas->w << ',' << canvas->h << ".\n";
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VALIDATE_WITH_DEV_MESSAGE(
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static_cast<int>(x - radius) >= 0
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, _("Circle doesn't fit on canvas.")
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, (formatter() << "x = " << x << ", radius = " << radius).str());
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VALIDATE_WITH_DEV_MESSAGE(
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static_cast<int>(y - radius) >= 0
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, _("Circle doesn't fit on canvas.")
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, (formatter() << "y = " << y << ", radius = " << radius).str());
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VALIDATE_WITH_DEV_MESSAGE(
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static_cast<int>(x + radius) < canvas->w
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, _("Circle doesn't fit on canvas.")
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, (formatter() << "x = " << x << ", radius = " << radius
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<< "', canvas width = " << canvas->w << ".").str());
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VALIDATE_WITH_DEV_MESSAGE(
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static_cast<int>(y + radius) < canvas->h
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, _("Circle doesn't fit on canvas.")
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, (formatter() << "y = " << y << ", radius = " << radius
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<< "', canvas height = " << canvas->h << ".").str());
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// lock the surface
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surface_lock locker(canvas);
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draw_circle(canvas, color_, x, y, radius);
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}
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/***** ***** ***** ***** ***** IMAGE ***** ***** ***** ***** *****/
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/** Definition of an image shape. */
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@ -1246,6 +1426,8 @@ void tcanvas::parse_cfg(const config& cfg)
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shapes_.push_back(new tline(data));
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} else if(type == "rectangle") {
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shapes_.push_back(new trectangle(data));
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} else if(type == "circle") {
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shapes_.push_back(new tcircle(data));
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} else if(type == "image") {
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shapes_.push_back(new timage(data));
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} else if(type == "text") {
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