b8c227a8f2
Conflicting demands arise in the implementation of class Fl_Xlib_Graphics_Driver for drawing images with the XRender library : 1) Issue #163 leads to use a bilinear filter to draw-and-scale images. 2) This tends to blur the edges of drawn areas which is bad for tiled images (that is because the edges get alpha values, even for an opaque source image). This commit resolves the conflict adding a means to detect whether the library is busy drawing a tiled image. If so, the bilinear filter is not applied, drawn areas don't have blurred edges, resulting in a nice tiling. With this commit, these test apps perform correctly: - tiled_image is correct at all scaling factor values also when modified to use a depth-3 or a depth-4 Fl_RGB_Image as tile; - unittests - Drawing Images is correct at all scaling factor values; - pixmap_browser scales correctly up and down JPEG and PNG images.
203 lines
6.5 KiB
C++
203 lines
6.5 KiB
C++
//
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// Tiled image code for the Fast Light Tool Kit (FLTK).
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//
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// Copyright 1998-2022 by Bill Spitzak and others.
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//
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// This library is free software. Distribution and use rights are outlined in
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// the file "COPYING" which should have been included with this file. If this
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// file is missing or damaged, see the license at:
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//
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// https://www.fltk.org/COPYING.php
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//
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// Please see the following page on how to report bugs and issues:
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//
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// https://www.fltk.org/bugs.php
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//
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#include <FL/Fl.H>
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#include <FL/Fl_Tiled_Image.H>
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#include <FL/Fl_Window.H>
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#include <FL/fl_draw.H>
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bool Fl_Tiled_Image::drawing_tiled_image_ = false;
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/**
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The constructors create a new tiled image containing the specified image.
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Use a width and height of 0 to tile the whole window/widget.
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\note Due to implementation constraints in FLTK 1.3.3 and later width
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and height of 0 may not work as expected when used as background image
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in widgets other than windows. You may need to center and clip the
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image (label) and set the label type to FL_NORMAL_LABEL. Doing so will
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let the tiled image fill the whole widget as its background image.
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Other combinations of label flags may or may not work.
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\code
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#include "bg.xpm"
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Fl_Pixmap *bg_xpm = new Fl_Pixmap(bg_xpm);
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Fl_Tiled_Image *bg_tiled = new Fl_Tiled_Image(bg_xpm,0,0);
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Fl_Box *box = new Fl_Box(40,40,300,100,"");
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box->box(FL_UP_BOX);
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box->labeltype(FL_NORMAL_LABEL);
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box->align(FL_ALIGN_INSIDE | FL_ALIGN_CENTER | FL_ALIGN_CLIP);
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box->image(bg_tiled);
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\endcode
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\note Setting an image (label) for a window may not work as expected due
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to implementation constraints in FLTK 1.3.x and maybe later. The reason
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is the way Fl::scheme() initializes the window's label type and image.
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A possible workaround is to use another Fl_Group as the only child widget
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and to set the background image for this group as described above.
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\todo Fix Fl_Tiled_Image as background image for widgets and windows
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and fix the implementation of Fl::scheme(const char *).
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*/
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Fl_Tiled_Image::Fl_Tiled_Image(Fl_Image *i, // I - Image to tile
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int W, // I - Width of tiled area
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int H) : // I - Height of tiled area
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Fl_Image(W,H,0) {
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image_ = i;
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alloc_image_ = 0;
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// giving to the tiled image the screen size may fail with multiscreen
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// configurations, so we leave it with w = h = 0 (STR #3106)
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// if (W == 0) w(Fl::w());
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// if (H == 0) h(Fl::h());
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}
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/**
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The destructor frees all memory and server resources that are used by
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the tiled image.
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*/
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Fl_Tiled_Image::~Fl_Tiled_Image() {
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if (alloc_image_) delete image_;
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}
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//
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// 'Fl_Tiled_Image::copy()' - Copy and resize a tiled image...
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//
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Fl_Image * // O - New image
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Fl_Tiled_Image::copy(int W, // I - New width
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int H) const { // I - New height
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return new Fl_Tiled_Image(image_, W, H);
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}
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//
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// 'Fl_Tiled_Image::color_average()' - Blend colors...
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//
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void
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Fl_Tiled_Image::color_average(Fl_Color c, // I - Color to blend with
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float i) { // I - Blend fraction
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if (!alloc_image_) {
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int W = image_->w(), H = image_->h();
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image_ = image_->copy(image_->data_w(), image_->data_h());
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image_->scale(W, H, 0, 1);
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alloc_image_ = 1;
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}
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image_->color_average(c, i);
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}
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//
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// 'Fl_Tiled_Image::desaturate()' - Convert the image to grayscale...
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//
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void
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Fl_Tiled_Image::desaturate() {
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if (!alloc_image_) {
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int W = image_->w(), H = image_->h();
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image_ = image_->copy(image_->data_w(), image_->data_h());
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image_->scale(W, H, 0, 1);
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alloc_image_ = 1;
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}
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image_->desaturate();
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}
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//
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// 'Fl_Tiled_Image::draw()' - Draw a tiled image.
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//
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/**
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Draws a tiled image.
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Tiled images can be used as background images for widgets and windows.
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However, due to implementation constraints, you must take care when
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setting label types and alignment flags. Only certain combinations work as
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expected, others may yield unexpected results and undefined behavior.
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This draw method can draw multiple copies of one image in an area given
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by \p X, \p Y, \p W, \p H.
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The optional arguments \p cx and \p cy can be used to crop the image
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starting at offsets (cx, cy). \p cx and \p cy must be \>= 0 (negative values
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are ignored). If one of the values is greater than the image width or height
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resp. (\p cx \>= image()->w() or \p cy \>= image()->h()) nothing is drawn,
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because the resulting image would be empty.
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After calculating the resulting image size the image is drawn as often
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as necessary to fill the given area, starting at the top left corner.
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If both \p W and \p H are 0 the image is repeated as often as necessary
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to fill the entire window, unless there is a valid clip region. If you
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want to fill only one particular widget's background, then you should
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either set a clip region in your draw() method or use the label alignment
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flags \p FL_ALIGN_INSIDE|FL_ALIGN_CLIP to make sure the image is clipped.
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This may be improved in a later version of the library.
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*/
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void
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Fl_Tiled_Image::draw(int X, // I - Starting X position
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int Y, // I - Starting Y position
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int W, // I - Width of area to be filled
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int H, // I - Height of area to be filled
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int cx, // I - "Source" X position
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int cy) { // I - "Source" Y position
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int iw = image_->w(); // effective image width
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int ih = image_->h(); // effective image height
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if (!iw || !ih) return;
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if (cx >= iw || cy >= ih) return;
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if (cx < 0) cx = 0; // ignore negative values
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if (cy < 0) cy = 0;
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// W and H null means the image is potentially as large as the current window
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// or widget. The latter can not be checked here, hence we use the whole
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// window as well and rely on appropriate clipping. See comments above.
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// This should be fixed! (AlbrechtS, 01 Mar 2015)
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if (W == 0 && H == 0 && Fl_Window::current()) {
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W = Fl_Window::current()->w();
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H = Fl_Window::current()->h();
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X = Y = 0;
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}
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if (W == 0 || H == 0) return;
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fl_push_clip(X, Y, W, H);
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drawing_tiled_image_ = true;
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if (cx > 0) iw -= cx; // crop image
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if (cy > 0) ih -= cy;
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for (int yy = Y; yy < Y+H; yy += ih) {
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if (fl_not_clipped(X,yy,W,ih)) {
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for (int xx = X; xx < X+W; xx += iw) {
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if (fl_not_clipped(xx,yy,iw,ih)) {
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image_->draw(xx,yy,iw,ih,cx,cy);
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}
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}
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}
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}
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drawing_tiled_image_ = false;
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fl_pop_clip();
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}
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