add checkerboard support

bottombuttongroup.cpp

@@ -1,5 +1,7 @@
 #include "bottombuttongroup.h"
 
+#include <functional>
+
 #include <QPushButton>
 #include <QVBoxLayout>
 #include <QDebug>
@@ -24,17 +26,27 @@ BottomButtonGroup::BottomButtonGroup(QWidget *parent)
                         "border-style: none;"
                         "}");
 
-    auto newBtn = [](QString text) -> QPushButton * {
+    auto newBtn = [](QString text, std::function<void()> func) -> QPushButton * {
         QPushButton * btn = new QPushButton(QIcon(QStringLiteral(":/icons/") + text), "");
         btn->setIconSize(QSize(40, 40));
         btn->setFixedSize(40, 40);
+        connect(btn, &QAbstractButton::clicked, btn, func);
         return btn;
     };
-    addButton(newBtn("zoom-original"));
-    addButton(newBtn("view-fullscreen"));
-    addButton(newBtn("zoom-in"));
-    addButton(newBtn("zoom-out"));
-    addButton(newBtn("object-rorate-right"));
+    addButton(newBtn("zoom-original", [this]() {
+        emit resetToOriginalBtnClicked();
+    }));
+    addButton(newBtn("view-fullscreen", [](){qDebug()<< "TODO: view-fullscreen";}));
+    addButton(newBtn("zoom-in", [this]() {
+        emit zoomInBtnClicked();
+    }));
+    addButton(newBtn("zoom-out", [this]() {
+        emit zoomOutBtnClicked();
+    }));
+    addButton(newBtn("view-background-checkerboard", [this]() {
+        emit toggleCheckerboardBtnClicked();
+    }));
+    addButton(newBtn("object-rorate-right", [](){qDebug()<< "TODO: object-rorate-right";}));
 }
 
 void BottomButtonGroup::addButton(QAbstractButton *button)

bottombuttongroup.h

@@ -11,6 +11,12 @@ public:
     explicit BottomButtonGroup(QWidget *parent = nullptr);
 
     void addButton(QAbstractButton *button);
+
+signals:
+    void resetToOriginalBtnClicked();
+    void zoomInBtnClicked();
+    void zoomOutBtnClicked();
+    void toggleCheckerboardBtnClicked();
 };
 
 #endif // BOTTOMBUTTONGROUP_H

graphicsview.cpp

@@ -18,31 +18,35 @@ GraphicsView::GraphicsView(QWidget *parent)
     setStyleSheet("background-color: rgba(0, 0, 0, 220);"
                   "border-radius: 3px;");
     setAcceptDrops(true);
+    setCheckerboardEnabled(false);
 }
 
 void GraphicsView::showImage(const QPixmap &pixmap)
 {
     resetTransform();
     scene()->showImage(pixmap);
-    if (!isThingSmallerThanWindowWith(transform())) {
-        m_enableFitInView = true;
-        fitInView(sceneRect(), Qt::KeepAspectRatio);
-    }
+    checkAndDoFitInView();
 }
 
 void GraphicsView::showText(const QString &text)
 {
+    resetTransform();
     scene()->showText(text);
+    checkAndDoFitInView();
 }
 
 void GraphicsView::showSvg(const QString &filepath)
 {
+    resetTransform();
     scene()->showSvg(filepath);
+    checkAndDoFitInView();
 }
 
 void GraphicsView::showGif(const QString &filepath)
 {
+    resetTransform();
     scene()->showGif(filepath);
+    checkAndDoFitInView();
 }
 
 GraphicsScene *GraphicsView::scene() const
@@ -55,6 +59,11 @@ void GraphicsView::setScene(GraphicsScene *scene)
     return QGraphicsView::setScene(scene);
 }
 
+void GraphicsView::toggleCheckerboard()
+{
+    setCheckerboardEnabled(!m_checkerboardEnabled);
+}
+
 void GraphicsView::mousePressEvent(QMouseEvent *event)
 {
     if (shouldIgnoreMousePressMoveEvent(event)) {
@@ -138,6 +147,11 @@ void GraphicsView::dropEvent(QDropEvent *event)
     const QMimeData * mimeData = event->mimeData();
 
     if (mimeData->hasUrls()) {
+        if (mimeData->urls().isEmpty()) {
+            // yeah, it's possible. dragging QQ's original sticker will trigger this, for example.
+            showText("File url list is empty");
+            return;
+        }
         QUrl url(mimeData->urls().first());
         QString filePath(url.toLocalFile());
 
@@ -188,3 +202,30 @@ bool GraphicsView::shouldIgnoreMousePressMoveEvent(const QMouseEvent *event) con
 
     return false;
 }
+
+void GraphicsView::checkAndDoFitInView()
+{
+    if (!isThingSmallerThanWindowWith(transform())) {
+        m_enableFitInView = true;
+        fitInView(sceneRect(), Qt::KeepAspectRatio);
+    }
+}
+
+void GraphicsView::setCheckerboardEnabled(bool enabled)
+{
+    m_checkerboardEnabled = enabled;
+    if (m_checkerboardEnabled) {
+        // Prepare background check-board pattern
+        QPixmap tilePixmap(0x20, 0x20);
+        tilePixmap.fill(QColor(30, 30, 30, 100));
+        QPainter tilePainter(&tilePixmap);
+        QColor color(40, 40, 40, 100);
+        tilePainter.fillRect(0, 0, 0x10, 0x10, color);
+        tilePainter.fillRect(0x10, 0x10, 0x10, 0x10, color);
+        tilePainter.end();
+
+        setBackgroundBrush(tilePixmap);
+    } else {
+        setBackgroundBrush(Qt::transparent);
+    }
+}

graphicsview.h

@@ -17,6 +17,9 @@ public:
     GraphicsScene * scene() const;
     void setScene(GraphicsScene *scene);
 
+public slots:
+    void toggleCheckerboard();
+
 private:
     void mousePressEvent(QMouseEvent * event) override;
     void mouseMoveEvent(QMouseEvent * event) override;
@@ -30,8 +33,11 @@ private:
 
     bool isThingSmallerThanWindowWith(const QTransform &transform) const;
     bool shouldIgnoreMousePressMoveEvent(const QMouseEvent *event) const;
+    void checkAndDoFitInView();
+    void setCheckerboardEnabled(bool enabled);
 
     bool m_enableFitInView = false;
+    bool m_checkerboardEnabled = false;
 };
 
 #endif // GRAPHICSVIEW_H

icons/view-background-checkerboard.svg

@@ -0,0 +1,87 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<!-- Created with Inkscape (http://www.inkscape.org/) -->
+
+<svg
+   xmlns:dc="http://purl.org/dc/elements/1.1/"
+   xmlns:cc="http://creativecommons.org/ns#"
+   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
+   xmlns:svg="http://www.w3.org/2000/svg"
+   xmlns="http://www.w3.org/2000/svg"
+   xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"
+   xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape"
+   width="32"
+   height="32"
+   viewBox="0 0 8.4666665 8.4666669"
+   version="1.1"
+   id="svg8"
+   inkscape:version="0.92.4 (5da689c313, 2019-01-14)"
+   sodipodi:docname="view-background-checkerboard.svg">
+  <defs
+     id="defs2" />
+  <sodipodi:namedview
+     id="base"
+     pagecolor="#000000"
+     bordercolor="#666666"
+     borderopacity="1.0"
+     inkscape:pageopacity="0.69803922"
+     inkscape:pageshadow="2"
+     inkscape:zoom="44.8"
+     inkscape:cx="14.891202"
+     inkscape:cy="11.596232"
+     inkscape:document-units="px"
+     inkscape:current-layer="layer1"
+     showgrid="false"
+     units="px"
+     inkscape:pagecheckerboard="true"
+     inkscape:window-width="1920"
+     inkscape:window-height="1001"
+     inkscape:window-x="-9"
+     inkscape:window-y="-9"
+     inkscape:window-maximized="1" />
+  <metadata
+     id="metadata5">
+    <rdf:RDF>
+      <cc:Work
+         rdf:about="">
+        <dc:format>image/svg+xml</dc:format>
+        <dc:type
+           rdf:resource="http://purl.org/dc/dcmitype/StillImage" />
+        <dc:title />
+      </cc:Work>
+    </rdf:RDF>
+  </metadata>
+  <g
+     inkscape:label="Layer 1"
+     inkscape:groupmode="layer"
+     id="layer1"
+     transform="translate(0,-288.5333)">
+    <rect
+       style="fill:#ffffff;fill-opacity:0.87058824;stroke:none;stroke-width:0.37041664;stroke-miterlimit:4;stroke-dasharray:none;stroke-opacity:1"
+       id="rect814"
+       width="2.7434142"
+       height="2.9153748"
+       x="1.5945871"
+       y="289.86566" />
+    <rect
+       style="fill:#ffffff;fill-opacity:0.87058824;stroke:none;stroke-width:0.37041664;stroke-miterlimit:4;stroke-dasharray:none;stroke-opacity:1"
+       id="rect814-4"
+       width="2.6871748"
+       height="2.9440556"
+       x="4.3380013"
+       y="292.78696" />
+    <rect
+       style="fill:#ffffff;fill-opacity:0.07843137;stroke:#ffffff;stroke-width:0;stroke-miterlimit:4;stroke-dasharray:none;stroke-opacity:1"
+       id="rect814-2"
+       width="2.7455406"
+       height="2.9440758"
+       x="1.5924606"
+       y="292.78696" />
+    <rect
+       style="fill:#ffffff;fill-opacity:0.07843137;stroke:#ffffff;stroke-width:0;stroke-miterlimit:4;stroke-dasharray:none;stroke-opacity:1"
+       id="rect814-2-6"
+       width="2.6982937"
+       height="2.9440918"
+       x="4.3380013"
+       y="289.83694" />
+  </g>
+</svg>

mainwindow.cpp

@@ -57,6 +57,15 @@ MainWindow::MainWindow(QWidget *parent) :
 
     m_bottomButtonGroup = new BottomButtonGroup(this);
 
+    connect(m_bottomButtonGroup, &BottomButtonGroup::resetToOriginalBtnClicked,
+            this, [ = ](){ pictureView->setTransform(QTransform()); });
+    connect(m_bottomButtonGroup, &BottomButtonGroup::zoomInBtnClicked,
+            this, [ = ](){ pictureView->scale(1.25, 1.25); });
+    connect(m_bottomButtonGroup, &BottomButtonGroup::zoomOutBtnClicked,
+            this, [ = ](){ pictureView->scale(0.75, 0.75); });
+    connect(m_bottomButtonGroup, &BottomButtonGroup::toggleCheckerboardBtnClicked,
+            this, [ = ](){ pictureView->toggleCheckerboard(); });
+
     this->setGeometry(
         QStyle::alignedRect(
             Qt::LeftToRight,

resources.qrc

@@ -5,5 +5,6 @@
         <file>icons/view-fullscreen.svg</file>
         <file>icons/zoom-original.svg</file>
         <file>icons/object-rorate-right.svg</file>
+        <file>icons/view-background-checkerboard.svg</file>
     </qresource>
 </RCC>