Snapshot_mask cannot handle font edge pixels perfectly

[q962 (提及)]

The code is very simple

	for ( GtkWidget* child = gtk_widget_get_first_child( ( gpointer )self ); child;
	      child            = gtk_widget_get_next_sibling( child ) ) {
		gtk_widget_snapshot_child( ( gpointer )self, child, snapshot );
	}


	gtk_snapshot_push_mask( snapshot, GSK_MASK_MODE_ALPHA );

	GtkSnapshot* child_snapshot = gtk_snapshot_new();
	for ( GtkWidget* child = gtk_widget_get_first_child( ( gpointer )self ); child;
	      child            = gtk_widget_get_next_sibling( child ) ) {
		gtk_widget_snapshot_child( ( gpointer )self, child, child_snapshot );
	}
	gtk_snapshot_append_node( snapshot, gtk_snapshot_free_to_node( child_snapshot ) );
	gtk_snapshot_pop( snapshot );

	gtk_snapshot_append_color( snapshot, &color, &GRAPHENE_RECT_INIT( 0, 0, width / 2, height ) );
	gtk_snapshot_pop( snapshot );

I don’t know how to improve it.

who can help me?

[q962 (提及)]

I think it should be forbidden to draw fonts under the mask area, by adding a clipping to the font, the problem may be solved.

[q962 (提及)]

	{
		gtk_snapshot_push_clip( snapshot, &GRAPHENE_RECT_INIT( offset, 0, width, height ) );
		GtkSnapshot* child_snapshot = gtk_snapshot_new();
		for ( GtkWidget* child = gtk_widget_get_first_child( ( gpointer )self ); child;
		      child            = gtk_widget_get_next_sibling( child ) ) {
			gtk_widget_snapshot_child( ( gpointer )self, child, child_snapshot );
		}
		gtk_snapshot_append_node( snapshot, gtk_snapshot_free_to_node( child_snapshot ) );
		gtk_snapshot_pop( snapshot );
	}

	gtk_snapshot_push_mask( snapshot, GSK_MASK_MODE_ALPHA );
	GtkSnapshot* child_snapshot = gtk_snapshot_new();
	for ( GtkWidget* child = gtk_widget_get_first_child( ( gpointer )self ); child;
	      child            = gtk_widget_get_next_sibling( child ) ) {
		gtk_widget_snapshot_child( ( gpointer )self, child, child_snapshot );
	}
	gtk_snapshot_append_node( snapshot, gtk_snapshot_free_to_node( child_snapshot ) );
	gtk_snapshot_pop( snapshot );
	gtk_snapshot_append_color( snapshot, &color, &GRAPHENE_RECT_INIT( 0, 0, offset, height ) );
	gtk_snapshot_pop( snapshot );

[Maximiliano]

What kind of widgets are composing the letters?

[matthiasc (Matthias Clasen)]

I don’t understand what the code is trying to achieve, and I don’t understand what is wrong with the screenshot.

[q962 (提及)]

Putting the two pictures together, it is easy to see the problem

What that code does is: fill part of the word with the specified color

[q962 (提及)]

it’s not the focus
I am dealing with the content of the painting.
can be seen as a progress bar

[q962 (提及)]

original plan
^
|
|   +-------+
|   | color |
|   | fill  |
| +-+-------+ - - - - +
|
+ +-text text text text

after modification
^
|
|   +-------+
|   | color |
|   | fill  |
| +-+-------+ - - - - +
|
+ +-          text text

The difference between the two schemes is what needs to be drawn.

In the original plan, I drew the characters in the whole area, but gtk can’t handle the color of the edge very well.

So I made a modification. Divide the content that needs to be drawn into two halves, one half draws color, and the other half draws text

[matthiasc (Matthias Clasen)]

Sorry, I still don’t understand what your problem with ‘edge pixels’ is.

In general, I would recommend to use text rendering apis to influence how text is rendered.

PangoLayout and PangoAttributes let you render parts of text with different colors.

[q962 (提及)]

Notice the white outline of the first line of text?

about ‘edge’: Sorry, I’m using Google Translate so it doesn’t describe well what I mean.
Can you understand if I replace it with “contour”?

I haven’t learned how to use pango yet.

For the functionality I currently need, using a mask is sufficient.