Add checkbox for a transparent BG when exporting image (#1344)

editor/src/messages/dialog/export_dialog/export_dialog_message.rs

@@ -9,6 +9,7 @@ pub enum ExportDialogMessage {
 	FileName(String),
 	FileType(FileType),
 	ScaleFactor(f64),
+	TransparentBackground(bool),
 	ExportBounds(ExportBounds),
 
 	Submit,

editor/src/messages/dialog/export_dialog/export_dialog_message_handler.rs

@@ -2,7 +2,7 @@ use crate::messages::frontend::utility_types::{ExportBounds, FileType};
 use crate::messages::layout::utility_types::layout_widget::{Layout, LayoutGroup, PropertyHolder, Widget, WidgetCallback, WidgetHolder, WidgetLayout};
 use crate::messages::layout::utility_types::misc::LayoutTarget;
 use crate::messages::layout::utility_types::widgets::button_widgets::TextButton;
-use crate::messages::layout::utility_types::widgets::input_widgets::{DropdownEntryData, DropdownInput, NumberInput, RadioEntryData, RadioInput, TextInput};
+use crate::messages::layout::utility_types::widgets::input_widgets::{CheckboxInput, DropdownEntryData, DropdownInput, NumberInput, RadioEntryData, RadioInput, TextInput};
 use crate::messages::layout::utility_types::widgets::label_widgets::{Separator, SeparatorDirection, SeparatorType, TextLabel};
 use crate::messages::prelude::*;
 
@@ -15,6 +15,7 @@ pub struct ExportDialogMessageHandler {
 	pub file_type: FileType,
 	pub scale_factor: f64,
 	pub bounds: ExportBounds,
+	pub transparent_background: bool,
 	pub artboards: HashMap<LayerId, String>,
 	pub has_selection: bool,
 }
@@ -24,7 +25,8 @@ impl MessageHandler<ExportDialogMessage, ()> for ExportDialogMessageHandler {
 		match message {
 			ExportDialogMessage::FileName(name) => self.file_name = name,
 			ExportDialogMessage::FileType(export_type) => self.file_type = export_type,
-			ExportDialogMessage::ScaleFactor(x) => self.scale_factor = x,
+			ExportDialogMessage::ScaleFactor(factor) => self.scale_factor = factor,
+			ExportDialogMessage::TransparentBackground(transparent_background) => self.transparent_background = transparent_background,
 			ExportDialogMessage::ExportBounds(export_area) => self.bounds = export_area,
 
 			ExportDialogMessage::Submit => responses.add_front(DocumentMessage::ExportDocument {
@@ -32,6 +34,7 @@ impl MessageHandler<ExportDialogMessage, ()> for ExportDialogMessageHandler {
 				file_type: self.file_type,
 				scale_factor: self.scale_factor,
 				bounds: self.bounds,
+				transparent_background: self.file_type != FileType::Jpg && self.transparent_background,
 			}),
 		}
 
@@ -120,6 +123,24 @@ impl PropertyHolder for ExportDialogMessageHandler {
 			})),
 		];
 
+		let transparent_background = vec![
+			WidgetHolder::new(Widget::TextLabel(TextLabel {
+				value: "Transparency".into(),
+				table_align: true,
+				..Default::default()
+			})),
+			WidgetHolder::new(Widget::Separator(Separator {
+				separator_type: SeparatorType::Unrelated,
+				direction: SeparatorDirection::Horizontal,
+			})),
+			WidgetHolder::new(Widget::CheckboxInput(CheckboxInput {
+				checked: self.transparent_background,
+				disabled: self.file_type == FileType::Jpg,
+				on_update: WidgetCallback::new(move |value: &CheckboxInput| ExportDialogMessage::TransparentBackground(value.checked).into()),
+				..Default::default()
+			})),
+		];
+
 		let resolution = vec![
 			WidgetHolder::new(Widget::TextLabel(TextLabel {
 				value: "Scale Factor".into(),
@@ -174,6 +195,7 @@ impl PropertyHolder for ExportDialogMessageHandler {
 			LayoutGroup::Row { widgets: export_type },
 			LayoutGroup::Row { widgets: resolution },
 			LayoutGroup::Row { widgets: export_area },
+			LayoutGroup::Row { widgets: transparent_background },
 			LayoutGroup::Row { widgets: button_widgets },
 		]))
 	}

editor/src/messages/portfolio/document/document_message.rs

@@ -82,6 +82,7 @@ pub enum DocumentMessage {
 		file_type: FileType,
 		scale_factor: f64,
 		bounds: ExportBounds,
+		transparent_background: bool,
 	},
 	FlipSelectedLayers {
 		flip_axis: FlipAxis,

editor/src/messages/portfolio/document/document_message_handler.rs

@@ -370,6 +370,7 @@ impl MessageHandler<DocumentMessage, (u64, &InputPreprocessorMessageHandler, &Pe
 				file_type,
 				scale_factor,
 				bounds,
+				transparent_background,
 			} => {
 				let old_transforms = self.remove_document_transform();
 
@@ -383,7 +384,7 @@ impl MessageHandler<DocumentMessage, (u64, &InputPreprocessorMessageHandler, &Pe
 				let size = bounds[1] - bounds[0];
 				let transform = (DAffine2::from_translation(bounds[0]) * DAffine2::from_scale(size)).inverse();
 
-				let document = self.render_document(size, transform, persistent_data, DocumentRenderMode::Root);
+				let document = self.render_document(size, transform, transparent_background, persistent_data, DocumentRenderMode::Root);
 
 				self.restore_document_transform(old_transforms);
 
@@ -1011,7 +1012,8 @@ impl DocumentMessageHandler {
 			// Calculate the size of the region to be exported and generate an SVG of the artwork below this layer within that region
 			let transform = self.document_legacy.multiply_transforms(&layer_path).unwrap();
 			let size = DVec2::new(transform.transform_vector2(DVec2::new(1., 0.)).length(), transform.transform_vector2(DVec2::new(0., 1.)).length());
-			let svg = self.render_document(size, transform.inverse(), persistent_data, DocumentRenderMode::OnlyBelowLayerInFolder(&layer_path));
+			// TODO: Test if this would be better to have a transparent background
+			let svg = self.render_document(size, transform.inverse(), false, persistent_data, DocumentRenderMode::OnlyBelowLayerInFolder(&layer_path));
 
 			self.restore_document_transform(old_transforms);
 
@@ -1053,7 +1055,7 @@ impl DocumentMessageHandler {
 		DocumentLegacy::mark_children_as_dirty(&mut self.artboard_message_handler.artboards_document.root);
 	}
 
-	pub fn render_document(&mut self, size: DVec2, transform: DAffine2, persistent_data: &PersistentData, render_mode: DocumentRenderMode) -> String {
+	pub fn render_document(&mut self, size: DVec2, transform: DAffine2, transparent_background: bool, persistent_data: &PersistentData, render_mode: DocumentRenderMode) -> String {
 		// Render the document SVG code
 
 		let render_data = RenderData::new(&persistent_data.font_cache, ViewMode::Normal, None);
@@ -1063,20 +1065,26 @@ impl DocumentMessageHandler {
 			DocumentRenderMode::OnlyBelowLayerInFolder(below_layer_path) => (self.document_legacy.render_layers_below(below_layer_path, &render_data).unwrap(), None),
 			DocumentRenderMode::LayerCutout(layer_path, background) => (self.document_legacy.render_layer(layer_path, &render_data).unwrap(), Some(background)),
 		};
-		let artboards = self.artboard_message_handler.artboards_document.render_root(&render_data);
+		let artboards = match transparent_background {
+			false => self.artboard_message_handler.artboards_document.render_root(&render_data),
+			true => "".into(),
+		};
 		let outside_artboards_color = outside.map_or_else(
 			|| if self.artboard_message_handler.artboard_ids.is_empty() { "ffffff" } else { "222222" }.to_string(),
 			|col| col.rgba_hex(),
 		);
-		let outside_artboards = format!(r##"<rect x="0" y="0" width="100%" height="100%" fill="#{}" />"##, outside_artboards_color);
+		let outside_artboards = match transparent_background {
+			false => format!(r##"<rect x="0" y="0" width="100%" height="100%" fill="#{}" />"##, outside_artboards_color),
+			true => "".into(),
+		};
 		let matrix = transform
 			.to_cols_array()
 			.iter()
 			.enumerate()
 			.fold(String::new(), |acc, (i, entry)| acc + &(entry.to_string() + if i == 5 { "" } else { "," }));
 		let svg = format!(
-			r#"<svg xmlns="http://www.w3.org/2000/svg" preserveAspectRatio="none" viewBox="0 0 1 1" width="{}" height="{}">{}{}<g transform="matrix({})">{}{}</g></svg>"#,
-			size.x, size.y, "\n", outside_artboards, matrix, artboards, artwork
+			r#"<svg xmlns="http://www.w3.org/2000/svg" preserveAspectRatio="none" viewBox="0 0 1 1" width="{}" height="{}">{}{outside_artboards}<g transform="matrix({matrix})">{artboards}{artwork}</g></svg>"#,
+			size.x, size.y, "\n",
 		);
 
 		svg