Demos: Import Fire demo contributed by "pd".

Demos/Fire/.gitignore

@@ -0,0 +1,3 @@
+Fire
+*.o
+*.d

Demos/Fire/Fire.cpp

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+/* Fire.cpp - a (classic) graphics demo for Serenity, by pd.
+ * heavily based on the Fabien Sanglard's article:
+ * http://fabiensanglard.net/doom_fire_psx/index.html
+ *
+ * Future directions:
+ *  [X] This does suggest the need for a palletized graphics surface. Thanks kling!
+ *  [X] alternate column updates, or vertical interlacing. this would certainly alter
+ *      the effect, but the update load would be halved.
+ *  [/] scaled blit
+ *  [ ] dithering?
+ *  [X] inlining rand()
+ *  [/] precalculating and recycling random data
+ *  [ ] rework/expand palette
+ *  [ ] switch to use tsc values for perf check
+ *  [ ] handle mouse events differently for smoother painting (queue)
+ *  [ ] handle fire bitmap edges better
+*/
+
+#include <LibGUI/GApplication.h>
+#include <LibGUI/GLabel.h>
+#include <LibGUI/GPainter.h>
+#include <LibGUI/GWidget.h>
+#include <LibGUI/GWindow.h>
+#include <SharedGraphics/GraphicsBitmap.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+
+#define FIRE_WIDTH 320
+#define FIRE_HEIGHT 168
+#define FIRE_MAX 29
+
+const Color palette[] = {
+    Color(0x07, 0x07, 0x07), Color(0x1F, 0x07, 0x07), Color(0x2F, 0x0F, 0x07),
+    Color(0x47, 0x0F, 0x07), Color(0x57, 0x17, 0x07), Color(0x67, 0x1F, 0x07),
+    Color(0x77, 0x1F, 0x07), Color(0x9F, 0x2F, 0x07), Color(0xAF, 0x3F, 0x07),
+    Color(0xBF, 0x47, 0x07), Color(0xC7, 0x47, 0x07), Color(0xDF, 0x4F, 0x07),
+    Color(0xDF, 0x57, 0x07), Color(0xD7, 0x5F, 0x07), Color(0xD7, 0x5F, 0x07),
+    Color(0xD7, 0x67, 0x0F), Color(0xCF, 0x6F, 0x0F), Color(0xCF, 0x7F, 0x0F),
+    Color(0xCF, 0x87, 0x17), Color(0xC7, 0x87, 0x17), Color(0xC7, 0x8F, 0x17),
+    Color(0xC7, 0x97, 0x1F), Color(0xBF, 0x9F, 0x1F), Color(0xBF, 0xA7, 0x27),
+    Color(0xBF, 0xAF, 0x2F), Color(0xB7, 0xAF, 0x2F), Color(0xB7, 0xB7, 0x37),
+    Color(0xCF, 0xCF, 0x6F), Color(0xEF, 0xEF, 0xC7), Color(0xFF, 0xFF, 0xFF)
+};
+
+/* Random functions...
+ * These are from musl libc's prng/rand.c
+*/
+static uint64_t seed;
+
+void my_srand(unsigned s)
+{
+    seed = s - 1;
+}
+
+static int my_rand(void)
+{
+    seed = 6364136223846793005ULL * seed + 1;
+    return seed >> 33;
+}
+
+/*
+ * Fire Widget
+*/
+class Fire : public GWidget {
+public:
+    explicit Fire(GWidget* parent = nullptr);
+    virtual ~Fire() override;
+    void set_stat_label(GLabel* l) { stats = l; };
+
+private:
+    RetainPtr<GraphicsBitmap> bitmap;
+    GLabel* stats;
+
+    virtual void paint_event(GPaintEvent&) override;
+    virtual void timer_event(CTimerEvent&) override;
+    virtual void mousedown_event(GMouseEvent& event) override;
+    virtual void mousemove_event(GMouseEvent& event) override;
+    virtual void mouseup_event(GMouseEvent& event) override;
+
+    bool dragging;
+    int timeAvg;
+    int cycles;
+    int phase;
+};
+
+Fire::Fire(GWidget* parent)
+    : GWidget(parent)
+{
+    bitmap = GraphicsBitmap::create(GraphicsBitmap::Format::Indexed8, { 320, 200 });
+
+    /* Initialize fire palette */
+    for (int i = 0; i < 30; i++)
+        bitmap->set_palette_color(i, palette[i]);
+
+    /* Set remaining entries to white */
+    for (int i = 30; i < 256; i++)
+        bitmap->set_palette_color(i, Color::White);
+
+    dragging = false;
+    timeAvg = 0;
+    cycles = 0;
+    phase = 0;
+
+    my_srand(time(nullptr));
+    stop_timer();
+    start_timer(20);
+
+    /* Draw fire "source" on bottom row of pixels */
+    for (int i = 0; i < FIRE_WIDTH; i++)
+        bitmap->bits(bitmap->height() - 1)[i] = FIRE_MAX;
+
+    /* Set off initital paint event */
+    //update();
+}
+
+Fire::~Fire()
+{
+}
+
+void Fire::paint_event(GPaintEvent& event)
+{
+    CElapsedTimer timer;
+    timer.start();
+
+    GPainter painter(*this);
+    painter.add_clip_rect(event.rect());
+
+    /* Blit it! */
+    painter.draw_scaled_bitmap(event.rect(), *bitmap, bitmap->rect());
+
+    timeAvg += timer.elapsed();
+    cycles++;
+}
+
+void Fire::timer_event(CTimerEvent&)
+{
+    /* Update only even or odd columns per frame... */
+    phase++;
+    if (phase > 1)
+        phase = 0;
+
+    /* Paint our palettized buffer to screen */
+    for (int px = 0 + phase; px < FIRE_WIDTH; px += 2) {
+        for (int py = 1; py < 200; py++) {
+            int rnd = my_rand() % 3;
+
+            /* Calculate new pixel value, don't go below 0 */
+            byte nv = bitmap->bits(py)[px];
+            if (nv > 0)
+                nv -= (rnd & 1);
+
+            /* ...sigh... */
+            int epx = px + (1 - rnd);
+            if (epx < 0)
+                epx = 0;
+            else if (epx > FIRE_WIDTH)
+                epx = FIRE_WIDTH;
+
+            bitmap->bits(py - 1)[epx] = nv;
+        }
+    }
+
+    if ((cycles % 50) == 0) {
+        dbgprintf("%d total cycles. finished 50 in %d ms, avg %d ms\n", cycles, timeAvg, timeAvg / 50);
+        stats->set_text(String::format("%d ms", timeAvg / 50));
+        timeAvg = 0;
+    }
+
+    update();
+}
+
+/*
+ * Mouse handling events
+*/
+void Fire::mousedown_event(GMouseEvent& event)
+{
+    if (event.button() == GMouseButton::Left)
+        dragging = true;
+
+    return GWidget::mousedown_event(event);
+}
+
+/* FIXME: needs to account for the size of the window rect */
+void Fire::mousemove_event(GMouseEvent& event)
+{
+    if (dragging) {
+        if (event.y() >= 2 && event.y() < 398 && event.x() <= 638) {
+            int ypos = event.y() / 2;
+            int xpos = event.x() / 2;
+            bitmap->bits(ypos - 1)[xpos] = FIRE_MAX + 5;
+            bitmap->bits(ypos - 1)[xpos + 1] = FIRE_MAX + 5;
+            bitmap->bits(ypos)[xpos] = FIRE_MAX + 5;
+            bitmap->bits(ypos)[xpos + 1] = FIRE_MAX + 5;
+        }
+    }
+
+    return GWidget::mousemove_event(event);
+}
+
+void Fire::mouseup_event(GMouseEvent& event)
+{
+    if (event.button() == GMouseButton::Left)
+        dragging = false;
+
+    return GWidget::mouseup_event(event);
+}
+
+/*
+ * Main
+*/
+int main(int argc, char** argv)
+{
+    GApplication app(argc, argv);
+
+    auto* window = new GWindow;
+    window->set_should_exit_event_loop_on_close(true);
+    window->set_double_buffering_enabled(false);
+    window->set_title("Fire");
+    window->set_resizable(false);
+    window->set_rect(100, 100, 640, 400);
+
+    auto* fire = new Fire;
+    window->set_main_widget(fire);
+
+    auto* time = new GLabel(fire);
+    time->set_relative_rect({ 0, 4, 40, 10 });
+    time->move_by({ window->width() - time->width(), 0 });
+    time->set_foreground_color(Color::from_rgb(0x444444));
+    fire->set_stat_label(time);
+
+    window->show();
+    window->set_icon_path("/res/icons/16x16/app-demo.png");
+
+    return app.exec();
+}

Demos/Fire/Makefile

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+include ../../Makefile.common
+
+OBJS = \
+    Fire.o
+
+APP = Fire
+
+DEFINES += -DUSERLAND
+
+all: $(APP)
+
+$(APP): $(OBJS)
+	$(LD) -o $(APP) $(LDFLAGS) $(OBJS) -lgui -lcore -lc
+
+.cpp.o:
+	@echo "CXX $<"; $(CXX) $(CXXFLAGS) -o $@ -c $<
+
+-include $(OBJS:%.o=%.d)
+
+clean:
+	@echo "CLEAN"; rm -f $(APP) $(OBJS) *.d
+

Kernel/build-root-filesystem.sh

@@ -75,6 +75,7 @@ cp ../Applications/PaintBrush/PaintBrush mnt/bin/PaintBrush
 cp ../Demos/HelloWorld/HelloWorld mnt/bin/HelloWorld
 cp ../Demos/RetroFetch/RetroFetch mnt/bin/RetroFetch
 cp ../Demos/WidgetGallery/WidgetGallery mnt/bin/WidgetGallery
+cp ../Demos/Fire/Fire mnt/bin/Fire
 cp ../DevTools/VisualBuilder/VisualBuilder mnt/bin/VisualBuilder
 cp ../Games/Minesweeper/Minesweeper mnt/bin/Minesweeper
 cp ../Games/Snake/Snake mnt/bin/Snake

Kernel/makeall.sh

@@ -36,6 +36,7 @@ build_targets="$build_targets ../Shell"
 build_targets="$build_targets ../Demos/HelloWorld"
 build_targets="$build_targets ../Demos/RetroFetch"
 build_targets="$build_targets ../Demos/WidgetGallery"
+build_targets="$build_targets ../Demos/Fire"
 build_targets="$build_targets ." # the kernel
 
 for targ in $build_targets; do