PixelPaint: Add level sliders for brightness, contrast and gamma

This patch adds a basic dialog to change brightness, contrast and gamma
correction for the selected layer.

Userland/Applications/PixelPaint/CMakeLists.txt

@@ -9,6 +9,7 @@ compile_gml(PixelPaintWindow.gml PixelPaintWindowGML.h pixel_paint_window_gml)
 compile_gml(EditGuideDialog.gml EditGuideDialogGML.h edit_guide_dialog_gml)
 compile_gml(FilterGallery.gml FilterGalleryGML.h filter_gallery_gml)
 compile_gml(ResizeImageDialog.gml ResizeImageDialogGML.h resize_image_dialog_gml)
+compile_gml(LevelsDialog.gml LevelsDialogGML.h levels_dialog_gml)
 
 set(SOURCES
     CreateNewImageDialog.cpp
@@ -39,6 +40,8 @@ set(SOURCES
     Layer.cpp
     LayerListWidget.cpp
     LayerPropertiesWidget.cpp
+    LevelsDialogGML.h
+    LevelsDialog.cpp
     MainWidget.cpp
     Mask.cpp
     PaletteWidget.cpp

Userland/Applications/PixelPaint/IconBag.cpp

@@ -40,6 +40,7 @@ ErrorOr<IconBag> IconBag::try_create()
     icon_bag.merge_active_layer_up = TRY(Gfx::Bitmap::try_load_from_file("/res/icons/pixelpaint/merge-active-layer-up.png"));
     icon_bag.merge_active_layer_down = TRY(Gfx::Bitmap::try_load_from_file("/res/icons/pixelpaint/merge-active-layer-down.png"));
     icon_bag.filter = TRY(Gfx::Bitmap::try_load_from_file("/res/icons/pixelpaint/filter.png"));
+    icon_bag.levels = TRY(Gfx::Bitmap::try_load_from_file("/res/icons/pixelpaint/levels.png"));
 
     return icon_bag;
 }

Userland/Applications/PixelPaint/IconBag.h

@@ -41,5 +41,6 @@ struct IconBag final {
     RefPtr<Gfx::Bitmap> merge_active_layer_up { nullptr };
     RefPtr<Gfx::Bitmap> merge_active_layer_down { nullptr };
     RefPtr<Gfx::Bitmap> filter { nullptr };
+    RefPtr<Gfx::Bitmap> levels { nullptr };
 };
 }

Userland/Applications/PixelPaint/LevelsDialog.cpp

@@ -0,0 +1,158 @@
+/*
+ * Copyright (c) 2022, Torsten Engelmann <engelTorsten@gmx.de>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include "LevelsDialog.h"
+#include <Applications/PixelPaint/LevelsDialogGML.h>
+#include <LibGUI/Button.h>
+#include <LibGUI/Label.h>
+#include <LibGUI/ValueSlider.h>
+
+namespace PixelPaint {
+
+LevelsDialog::LevelsDialog(GUI::Window* parent_window, ImageEditor* editor)
+    : GUI::Dialog(parent_window)
+{
+    set_title("Levels");
+    set_icon(parent_window->icon());
+
+    auto& main_widget = set_main_widget<GUI::Widget>();
+    if (!main_widget.load_from_gml(levels_dialog_gml))
+        VERIFY_NOT_REACHED();
+
+    resize(305, 202);
+    set_resizable(false);
+
+    m_editor = editor;
+
+    m_brightness_slider = main_widget.find_descendant_of_type_named<GUI::ValueSlider>("brightness_slider");
+    m_contrast_slider = main_widget.find_descendant_of_type_named<GUI::ValueSlider>("contrast_slider");
+    m_gamma_slider = main_widget.find_descendant_of_type_named<GUI::ValueSlider>("gamma_slider");
+    auto context_label = main_widget.find_descendant_of_type_named<GUI::Label>("context_label");
+    auto apply_button = main_widget.find_descendant_of_type_named<GUI::Button>("apply_button");
+    auto cancel_button = main_widget.find_descendant_of_type_named<GUI::Button>("cancel_button");
+
+    VERIFY(m_brightness_slider);
+    VERIFY(m_contrast_slider);
+    VERIFY(m_gamma_slider);
+    VERIFY(context_label);
+    VERIFY(apply_button);
+    VERIFY(cancel_button);
+    VERIFY(m_editor->active_layer());
+
+    context_label->set_text(String::formatted("Working on layer: {}", m_editor->active_layer()->name()));
+    m_gamma_slider->set_value(100);
+
+    m_brightness_slider->on_change = [this](auto) {
+        generate_new_image();
+    };
+
+    m_contrast_slider->on_change = [this](auto) {
+        generate_new_image();
+    };
+
+    m_gamma_slider->on_change = [this](auto) {
+        generate_new_image();
+    };
+
+    apply_button->on_click = [this](auto) {
+        if (m_did_change) {
+            m_editor->on_modified_change(true);
+            m_editor->did_complete_action();
+        }
+
+        cleanup_resources();
+        done(ExecResult::OK);
+    };
+
+    cancel_button->on_click = [this](auto) {
+        done(ExecResult::Cancel);
+    };
+}
+
+void LevelsDialog::revert_possible_changes()
+{
+    // FIXME: Find a faster way to revert all the changes that we have done.
+    if (m_did_change && m_reference_bitmap) {
+        for (int x = 0; x < m_reference_bitmap->width(); x++) {
+            for (int y = 0; y < m_reference_bitmap->height(); y++) {
+                m_editor->active_layer()->content_bitmap().set_pixel(x, y, m_reference_bitmap->get_pixel(x, y));
+            }
+        }
+        m_editor->layers_did_change();
+    }
+
+    cleanup_resources();
+}
+
+void LevelsDialog::generate_new_image()
+{
+    (void)ensure_reference_bitmap();
+    if (m_reference_bitmap.is_null())
+        return;
+
+    generate_precomputed_color_correction();
+    Color current_pixel_color;
+    Color new_pixel_color;
+    Gfx::StorageFormat storage_format = Gfx::determine_storage_format(m_editor->active_layer()->content_bitmap().format());
+
+    for (int x = 0; x < m_reference_bitmap->width(); x++) {
+        for (int y = 0; y < m_reference_bitmap->height(); y++) {
+            current_pixel_color = m_reference_bitmap->get_pixel(x, y);
+
+            new_pixel_color.set_alpha(current_pixel_color.alpha());
+            new_pixel_color.set_red(m_precomputed_color_correction[current_pixel_color.red()]);
+            new_pixel_color.set_green(m_precomputed_color_correction[current_pixel_color.green()]);
+            new_pixel_color.set_blue(m_precomputed_color_correction[current_pixel_color.blue()]);
+
+            switch (storage_format) {
+            case Gfx::StorageFormat::BGRx8888:
+            case Gfx::StorageFormat::BGRA8888:
+                m_editor->active_layer()->content_bitmap().scanline(y)[x] = new_pixel_color.value();
+                break;
+            default:
+                m_editor->active_layer()->content_bitmap().set_pixel(x, y, new_pixel_color);
+            }
+        }
+    }
+
+    m_editor->active_layer()->did_modify_bitmap();
+    m_did_change = true;
+}
+
+ErrorOr<void> LevelsDialog::ensure_reference_bitmap()
+{
+    if (m_reference_bitmap.is_null())
+        m_reference_bitmap = TRY(m_editor->active_layer()->content_bitmap().clone());
+
+    return {};
+}
+
+void LevelsDialog::cleanup_resources()
+{
+    if (m_reference_bitmap)
+        m_reference_bitmap = nullptr;
+}
+
+void LevelsDialog::generate_precomputed_color_correction()
+{
+    int delta_brightness = m_brightness_slider->value();
+    float contrast_correction_factor = static_cast<float>(259 * (m_contrast_slider->value() + 255) / static_cast<float>(255 * (259 - m_contrast_slider->value())));
+    float gamma_correction = 1 / (m_gamma_slider->value() / 100.0);
+
+    for (int color_val = 0; color_val < 256; color_val++) {
+        m_precomputed_color_correction[color_val] = color_val + delta_brightness;
+        m_precomputed_color_correction[color_val] = m_precomputed_color_correction[color_val] < 0 ? 0 : m_precomputed_color_correction[color_val];
+        m_precomputed_color_correction[color_val] = m_precomputed_color_correction[color_val] > 255 ? 255 : m_precomputed_color_correction[color_val];
+
+        m_precomputed_color_correction[color_val] = 255 * AK::pow<float>((m_precomputed_color_correction[color_val] / 255.0), gamma_correction);
+
+        m_precomputed_color_correction[color_val] = contrast_correction_factor * (m_precomputed_color_correction[color_val] - 128) + 128;
+        m_precomputed_color_correction[color_val] = m_precomputed_color_correction[color_val] < 0 ? 0 : m_precomputed_color_correction[color_val];
+        m_precomputed_color_correction[color_val] = m_precomputed_color_correction[color_val] > 255 ? 255 : m_precomputed_color_correction[color_val];
+    }
+}
+
+}

Userland/Applications/PixelPaint/LevelsDialog.gml

@@ -0,0 +1,87 @@
+@GUI::Frame {
+    fill_with_background_color: true
+    layout: @GUI::VerticalBoxLayout {
+        margins: [4]
+    }
+
+    @GUI::Widget {
+        shrink_to_fit: true
+        layout: @GUI::VerticalBoxLayout {}
+
+        @GUI::Label {
+            name: "context_label"
+            enabled: true
+            fixed_height: 20
+            visible: true
+            text: "Working on Background"
+            text_alignment: "CenterLeft"
+        }
+
+        @GUI::Label {
+            enabled: true
+            fixed_height: 20
+            visible: true
+            text: "Brightness"
+            text_alignment: "Left"
+        }
+
+        @GUI::ValueSlider {
+            name: "brightness_slider"
+            value: 0
+            max: 255
+            min: -255
+            page_step: 10
+        }
+
+        @GUI::Label {
+            enabled: true
+            fixed_height: 20
+            visible: true
+            text: "Contrast"
+            text_alignment: "Left"
+        }
+
+        @GUI::ValueSlider {
+            name: "contrast_slider"
+            value: 0
+            max: 255
+            min: -255
+            page_step: 10
+        }
+
+        @GUI::Label {
+            enabled: true
+            fixed_height: 20
+            visible: true
+            text: "Gamma"
+            text_alignment: "Left"
+        }
+
+        @GUI::ValueSlider {
+            name: "gamma_slider"
+            value: 100
+            max: 350
+            min: 1
+            page_step: 10
+        }
+
+        @GUI::HorizontalSeparator {}
+    }
+
+    @GUI::Widget {
+        layout: @GUI::HorizontalBoxLayout {}
+        fixed_height: 22
+
+        @GUI::Layout::Spacer {}
+
+        @GUI::DialogButton {
+            name: "apply_button"
+            text: "OK"
+        }
+
+        @GUI::DialogButton {
+            name: "cancel_button"
+            text: "Cancel"
+        }
+    }
+}

Userland/Applications/PixelPaint/LevelsDialog.h

@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) 2022, Torsten Engelmann <engelTorsten@gmx.de>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include "ImageEditor.h"
+#include "Layer.h"
+#include <LibGUI/Dialog.h>
+
+namespace PixelPaint {
+
+class LevelsDialog final : public GUI::Dialog {
+    C_OBJECT(LevelsDialog);
+
+public:
+    void revert_possible_changes();
+
+private:
+    LevelsDialog(GUI::Window* parent_window, ImageEditor*);
+
+    ImageEditor* m_editor { nullptr };
+    RefPtr<Gfx::Bitmap> m_reference_bitmap { nullptr };
+    RefPtr<GUI::ValueSlider> m_brightness_slider = { nullptr };
+    RefPtr<GUI::ValueSlider> m_contrast_slider = { nullptr };
+    RefPtr<GUI::ValueSlider> m_gamma_slider = { nullptr };
+    bool m_did_change = false;
+    int m_precomputed_color_correction[256];
+
+    ErrorOr<void> ensure_reference_bitmap();
+    void generate_new_image();
+    void cleanup_resources();
+    void generate_precomputed_color_correction();
+};
+
+}

Userland/Applications/PixelPaint/MainWidget.cpp

@@ -12,6 +12,7 @@
 #include "EditGuideDialog.h"
 #include "FilterGallery.h"
 #include "FilterParams.h"
+#include "LevelsDialog.h"
 #include "ResizeImageDialog.h"
 #include <Applications/PixelPaint/PixelPaintWindowGML.h>
 #include <LibConfig/Client.h>
@@ -701,6 +702,15 @@ void MainWidget::initialize_menubar(GUI::Window& window)
     auto& help_menu = window.add_menu("&Help");
     help_menu.add_action(GUI::CommonActions::make_about_action("Pixel Paint", GUI::Icon::default_icon("app-pixel-paint"), &window));
 
+    m_levels_dialog_action = GUI::Action::create(
+        "Change &Levels...", { Mod_Ctrl, Key_L }, g_icon_bag.levels, [&](auto&) {
+            auto* editor = current_image_editor();
+            VERIFY(editor);
+            auto dialog = PixelPaint::LevelsDialog::construct(&window, editor);
+            if (dialog->exec() != GUI::Dialog::ExecResult::OK)
+                dialog->revert_possible_changes();
+        });
+
     auto& toolbar = *find_descendant_of_type_named<GUI::Toolbar>("toolbar");
     toolbar.add_action(*m_new_image_action);
     toolbar.add_action(*m_open_image_action);
@@ -715,6 +725,7 @@ void MainWidget::initialize_menubar(GUI::Window& window)
     toolbar.add_action(*m_zoom_in_action);
     toolbar.add_action(*m_zoom_out_action);
     toolbar.add_action(*m_reset_zoom_action);
+
     m_zoom_combobox = toolbar.add<GUI::ComboBox>();
     m_zoom_combobox->set_max_width(75);
     m_zoom_combobox->set_model(*GUI::ItemListModel<String>::create(s_suggested_zoom_levels));
@@ -752,6 +763,9 @@ void MainWidget::initialize_menubar(GUI::Window& window)
     m_zoom_combobox->on_return_pressed = [this]() {
         m_zoom_combobox->on_change(m_zoom_combobox->text(), GUI::ModelIndex());
     };
+
+    toolbar.add_separator();
+    toolbar.add_action(*m_levels_dialog_action);
 }
 
 void MainWidget::set_actions_enabled(bool enabled)

Userland/Applications/PixelPaint/MainWidget.h

@@ -81,6 +81,7 @@ private:
     RefPtr<GUI::Action> m_save_image_action;
     RefPtr<GUI::Action> m_save_image_as_action;
     RefPtr<GUI::Action> m_close_image_action;
+    RefPtr<GUI::Action> m_levels_dialog_action;
 
     RefPtr<GUI::Action> m_cut_action;
     RefPtr<GUI::Action> m_copy_action;