PixelPaint: Add a preview in FilterGallery

Now FilterGallery shows the preview of the currently selected filter
applied on the currently active layer

Userland/Applications/PixelPaint/CMakeLists.txt

@@ -17,6 +17,7 @@ set(SOURCES
     FilterGallery.cpp
     FilterGalleryGML.h
     FilterModel.cpp
+    FilterPreviewWidget.cpp
     Filters/Bloom.cpp
     Filters/BoxBlur3.cpp
     Filters/BoxBlur5.cpp

Userland/Applications/PixelPaint/FilterGallery.cpp

@@ -29,11 +29,13 @@ FilterGallery::FilterGallery(GUI::Window* parent_window, ImageEditor* editor)
     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");
     m_config_widget = main_widget.find_descendant_of_type_named<GUI::Widget>("config_widget");
+    m_preview_widget = main_widget.find_descendant_of_type_named<FilterPreviewWidget>("preview_widget");
 
     VERIFY(m_filter_tree);
     VERIFY(apply_button);
     VERIFY(cancel_button);
     VERIFY(m_config_widget);
+    VERIFY(m_preview_widget);
 
     auto filter_model = FilterModel::create(editor);
     m_filter_tree->set_model(filter_model);
@@ -41,20 +43,30 @@ FilterGallery::FilterGallery(GUI::Window* parent_window, ImageEditor* editor)
 
     m_filter_tree->on_selection_change = [this]() {
         auto selected_index = m_filter_tree->selection().first();
-        if (!selected_index.is_valid())
+        if (!selected_index.is_valid()) {
+            m_preview_widget->clear_filter();
             return;
+        }
 
         auto selected_filter = static_cast<const FilterModel::FilterInfo*>(selected_index.internal_data());
-        if (selected_filter->type != FilterModel::FilterInfo::Type::Filter)
+        if (selected_filter->type != FilterModel::FilterInfo::Type::Filter) {
+            m_preview_widget->clear_filter();
             return;
+        }
 
         m_selected_filter = selected_filter->filter;
+        m_selected_filter->on_settings_change = [&]() {
+            m_preview_widget->set_filter(m_selected_filter);
+        };
+        m_preview_widget->set_filter(m_selected_filter);
 
         m_selected_filter_config_widget = m_selected_filter->get_settings_widget();
         m_config_widget->remove_all_children();
         m_config_widget->add_child(*m_selected_filter_config_widget);
     };
 
+    m_preview_widget->set_bitmap(editor->active_layer()->bitmap().clone().release_value());
+
     apply_button->on_click = [this](auto) {
         if (!m_selected_filter) {
             done(ExecResult::ExecAborted);

Userland/Applications/PixelPaint/FilterGallery.gml

@@ -13,11 +13,29 @@
         }
 
         @GUI::Widget {
-            name: "config_widget"
-            layout: @GUI::VerticalBoxLayout {
+            layout:@GUI::VerticalBoxLayout {
                 margins: [4]
             }
 
+            @GUI::Widget {
+                name: "config_widget"
+
+                layout:@GUI::VerticalBoxLayout {
+                    margins: [4]
+                }
+            }
+
+            @GUI::GroupBox {
+                title: "Preview"
+                layout: @GUI::VerticalBoxLayout {
+                    margins: [4]
+                }
+
+                @PixelPaint::FilterPreviewWidget {
+                    name: "preview_widget"
+                }
+            }
+
         }
     }
 
@@ -29,6 +47,8 @@
 
         @GUI::Widget
 
+        
+
         @GUI::Button {
             name: "apply_button"
             text: "Apply"

Userland/Applications/PixelPaint/FilterGallery.h

@@ -6,6 +6,7 @@
 
 #pragma once
 
+#include "FilterPreviewWidget.h"
 #include "Filters/Filter.h"
 #include "ImageEditor.h"
 #include <LibGUI/Dialog.h>
@@ -19,6 +20,7 @@ private:
     FilterGallery(GUI::Window* parent_window, ImageEditor*);
     GUI::TreeView* m_filter_tree { nullptr };
     GUI::Widget* m_config_widget { nullptr };
+    FilterPreviewWidget* m_preview_widget { nullptr };
     RefPtr<GUI::Widget> m_selected_filter_config_widget { nullptr };
     Filter* m_selected_filter { nullptr };
 };

Userland/Applications/PixelPaint/FilterPreviewWidget.cpp

@@ -0,0 +1,67 @@
+/*
+ * Copyright (c) 2022, the SerenityOS developers.
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include "FilterPreviewWidget.h"
+#include <LibGUI/Painter.h>
+#include <LibGfx/Palette.h>
+#include <LibGfx/Rect.h>
+
+REGISTER_WIDGET(PixelPaint, FilterPreviewWidget);
+
+namespace PixelPaint {
+
+FilterPreviewWidget::FilterPreviewWidget()
+{
+}
+
+FilterPreviewWidget::~FilterPreviewWidget()
+{
+}
+
+void FilterPreviewWidget::set_bitmap(const RefPtr<Gfx::Bitmap>& bitmap)
+{
+    m_bitmap = bitmap;
+    clear_filter();
+}
+
+void FilterPreviewWidget::set_filter(Filter* filter)
+{
+    if (filter)
+        filter->apply(*m_filtered_bitmap, *m_bitmap);
+    else
+        m_filtered_bitmap = m_bitmap->clone().release_value();
+    repaint();
+}
+
+void FilterPreviewWidget::clear_filter()
+{
+    set_filter(nullptr);
+}
+
+void FilterPreviewWidget::paint_event(GUI::PaintEvent& event)
+{
+    GUI::Painter painter(*this);
+    painter.add_clip_rect(event.rect());
+    auto preview_rect = event.rect();
+    auto bitmap_rect = m_filtered_bitmap->rect();
+
+    int scaled_width, scaled_height, dx = 0, dy = 0;
+    if (preview_rect.height() > preview_rect.width()) {
+        scaled_width = preview_rect.width();
+        scaled_height = ((float)bitmap_rect.height() / bitmap_rect.width()) * scaled_width;
+        dy = (preview_rect.height() - scaled_height) / 2;
+    } else {
+        scaled_height = preview_rect.height();
+        scaled_width = ((float)bitmap_rect.width() / bitmap_rect.height()) * scaled_height;
+        dx = (preview_rect.width() - scaled_width) / 2;
+    }
+
+    Gfx::IntRect scaled_rect(preview_rect.x() + dx, preview_rect.y() + dy, scaled_width, scaled_height);
+
+    painter.draw_scaled_bitmap(scaled_rect, *m_filtered_bitmap, m_filtered_bitmap->rect());
+}
+
+}

Userland/Applications/PixelPaint/FilterPreviewWidget.h

@@ -0,0 +1,35 @@
+/*
+ * Copyright (c) 2022, the SerenityOS developers.
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include "Filters/Filter.h"
+#include "ImageEditor.h"
+#include "Layer.h"
+#include <LibGUI/Frame.h>
+#include <LibGfx/Bitmap.h>
+
+namespace PixelPaint {
+
+class FilterPreviewWidget final : public GUI::Frame {
+    C_OBJECT(FilterPreviewWidget);
+
+public:
+    virtual ~FilterPreviewWidget() override;
+    void set_bitmap(const RefPtr<Gfx::Bitmap>& bitmap);
+    void set_filter(Filter* filter);
+    void clear_filter();
+
+private:
+    explicit FilterPreviewWidget();
+
+    RefPtr<Gfx::Bitmap> m_bitmap;
+    RefPtr<Gfx::Bitmap> m_filtered_bitmap;
+
+    virtual void paint_event(GUI::PaintEvent&) override;
+};
+
+}

Userland/Applications/PixelPaint/Filters/Bloom.cpp

@@ -59,6 +59,7 @@ RefPtr<GUI::Widget> Bloom::get_settings_widget()
         luma_lower_slider.set_value(m_luma_lower);
         luma_lower_slider.on_change = [&](int value) {
             m_luma_lower = value;
+            update_preview();
         };
 
         auto& radius_container = m_settings_widget->add<GUI::Widget>();
@@ -75,6 +76,7 @@ RefPtr<GUI::Widget> Bloom::get_settings_widget()
         radius_slider.set_value(m_blur_radius);
         radius_slider.on_change = [&](int value) {
             m_blur_radius = value;
+            update_preview();
         };
     }
 

Userland/Applications/PixelPaint/Filters/FastBoxBlur.cpp

@@ -54,6 +54,7 @@ RefPtr<GUI::Widget> FastBoxBlur::get_settings_widget()
         radius_slider.set_value(m_radius);
         radius_slider.on_change = [&](int value) {
             m_radius = value;
+            update_preview();
         };
 
         auto& gaussian_container = m_settings_widget->add<GUI::Widget>();
@@ -66,6 +67,7 @@ RefPtr<GUI::Widget> FastBoxBlur::get_settings_widget()
         gaussian_checkbox.set_tooltip("A real gaussian blur can be approximated by running the box blur multiple times with different weights.");
         gaussian_checkbox.on_checked = [this](bool checked) {
             m_approximate_gauss = checked;
+            update_preview();
         };
     }
 

Userland/Applications/PixelPaint/Filters/Filter.cpp

@@ -37,4 +37,10 @@ void Filter::apply() const
     }
 }
 
+void Filter::update_preview()
+{
+    if (on_settings_change)
+        on_settings_change();
+}
+
 }

Userland/Applications/PixelPaint/Filters/Filter.h

@@ -27,9 +27,12 @@ public:
     Filter(ImageEditor* editor)
         : m_editor(editor) {};
 
+    Function<void(void)> on_settings_change;
+
 protected:
     ImageEditor* m_editor { nullptr };
     RefPtr<GUI::Widget> m_settings_widget { nullptr };
+    void update_preview();
 };
 
 }

Userland/Applications/PixelPaint/Filters/Sepia.cpp

@@ -42,6 +42,7 @@ RefPtr<GUI::Widget> Sepia::get_settings_widget()
         amount_slider.set_value(m_amount * 100);
         amount_slider.on_change = [&](int value) {
             m_amount = value * 0.01f;
+            update_preview();
         };
     }