Image: Add an option to crop on a single web element

src/image/imagearguments.cc

@@ -38,6 +38,7 @@ ImageCommandLineParser::ImageCommandLineParser(wkhtmltopdf::settings::ImageGloba
 	// addarg("scale-w",0,"Set width for resizing", new IntSetter(s.scale.width,"int"));
 	// addarg("scale-h",0,"Set height for resizing", new IntSetter(s.scale.height,"int"));
 
+	addarg("selector", 0, "Set a CSS2 selector that points to an element to crop on", new QStrSetter(s.selector, "selector"));
 	addarg("crop-x",0,"Set x coordinate for cropping", new IntSetter(s.crop.left,"int"));
 	addarg("crop-y",0,"Set y coordinate for cropping", new IntSetter(s.crop.top,"int"));
 	addarg("crop-w",0,"Set width for cropping", new IntSetter(s.crop.width,"int"));

src/image/imagedocparts.cc

@@ -118,5 +118,9 @@ void ImageCommandLineParser::outputExamples(Outputter * o) const {
 	o->verbatim("wkhtmltoimage http://www.google.com google.png\n");
 	o->paragraph("To convert a local HTML file to PNG:");
 	o->verbatim("wkhtmltoimage my.html my.png\n");
+	o->paragraph("To crop on a specific HTML element:");
+	o->verbatim("wkhtmltoimage --selector '#hplogo' https://google.com google.png\n");
+	o->paragraph("To crop a part of the element by an offset (use a negative offset for a margin):");
+	o->verbatim("wkhtmltoimage --selector '#hplogo' --crop-x 70 https://google.com google.png\n");
 	o->endSection();
 }

src/lib/imageconverter.cc

@@ -166,12 +166,28 @@ void ImageConverterPrivate::pagesLoaded(bool ok) {
 		fail();
 	}
 
-	if (settings.crop.left < 0) settings.crop.left = 0;
-	if (settings.crop.top < 0) settings.crop.top = 0;
-	if (settings.crop.width < 0) settings.crop.width = 1000000;
-	if (settings.crop.height < 0) settings.crop.height = 1000000;
-	QRect rect = QRect(QPoint(0,0), loaderObject->page.viewportSize()).intersected(
-		QRect(settings.crop.left,settings.crop.top,settings.crop.width,settings.crop.height));
+	QRect rect;
+	if (settings.selector != "") {
+		QWebElement elem = frame->findFirstElement(settings.selector);
+		if (elem.isNull()) {
+			emit out.error("No element matched the selector");
+			fail();
+			return;
+		}
+		rect = elem.geometry().adjusted(
+			settings.crop.left == settings::CropSettings::DEFAULT ? 0 : settings.crop.left,
+			settings.crop.top == settings::CropSettings::DEFAULT ? 0 : settings.crop.top,
+			settings.crop.width == settings::CropSettings::DEFAULT ? 0 : settings.crop.width,
+			settings.crop.height == settings::CropSettings::DEFAULT ? 0 : settings.crop.height);
+
+	} else { 
+		if (settings.crop.left < 0) settings.crop.left = 0;
+		if (settings.crop.top < 0) settings.crop.top = 0;
+		if (settings.crop.width < 0) settings.crop.width = 1000000;
+		if (settings.crop.height < 0) settings.crop.height = 1000000;
+		rect = QRect(QPoint(0,0), loaderObject->page.viewportSize()).intersected(
+			QRect(settings.crop.left,settings.crop.top,settings.crop.width,settings.crop.height));
+	}
 	if (rect.width() == 0 || rect.height() == 0) {
 		emit out.error("Will not output an empty image");
 		fail();

src/lib/imagesettings.cc

@@ -48,17 +48,20 @@ struct DLL_LOCAL ReflectImpl<ImageGlobal>: public ReflectClass {
 		WKHTMLTOPDF_REFLECT(in);
 		WKHTMLTOPDF_REFLECT(out);
 		WKHTMLTOPDF_REFLECT(fmt);
+		WKHTMLTOPDF_REFLECT(selector);
 		WKHTMLTOPDF_REFLECT(quality);
 		WKHTMLTOPDF_REFLECT(loadGlobal);
 		WKHTMLTOPDF_REFLECT(loadPage);
 	}
 };
 
+const int CropSettings::DEFAULT = std::numeric_limits<int>::min();
+
 CropSettings::CropSettings():
-	left(-1),
-	top(-1),
-	width(-1),
-	height(-1) {}
+	left(DEFAULT),
+	top(DEFAULT),
+	width(DEFAULT),
+	height(DEFAULT) {}
 
 ImageGlobal::ImageGlobal():
 	logLevel(Info),
@@ -67,6 +70,7 @@ ImageGlobal::ImageGlobal():
 	in(""),
 	out(""),
 	fmt(""),
+	selector(""),
 	screenWidth(1024),
 	screenHeight(0),
 	quality(94),

src/lib/imagesettings.hh

@@ -25,6 +25,7 @@
 #include <logging.hh>
 #include <loadsettings.hh>
 #include <websettings.hh>
+#include <limits>
 
 #include <dllbegin.inc>
 namespace wkhtmltopdf {
@@ -41,6 +42,8 @@ struct DLL_PUBLIC CropSettings {
 	int width;
 	//! Cropping height/h dime
 	int height;
+
+	static const int DEFAULT;
 };
 
 /*! \brief Class holding all user settings.
@@ -74,6 +77,9 @@ struct DLL_PUBLIC ImageGlobal {
 	QString out;
 	//! The output format
 	QString fmt;
+
+	//! Set the CSS selector of an element to crop on
+	QString selector;
 
 	//! Set the screen width
 	int screenWidth;