我正在尝试在使用 pango 构建的图中标记 y 轴。
我无法将文本定向为沿 y 轴垂直向上运行。
代码的相关部分是:
#include <gtkmm.h>
Pango::FontDescription font;
cr->save(); // where cr is Glib::RefPtr<Cairo::Context> const &
cr->set_source_rgba(1.0,1.0,1.0,0.5);
font.set_family("Monospace");
font.set_style(Pango::STYLE_ITALIC);
font.set_weight(Pango::WEIGHT_BOLD);
font.set_absolute_size(20);
Glib::RefPtr<Pango::Layout> x_axis_label = this->create_pango_layout("x-axis label");
x_axis_label->set_font_description(font);
cr->move_to(0.38,0.465);
x_axis_label->show_in_cairo_context(cr);
// so far so good, renders as expected
// now trying to render the y-axis label
Glib::RefPtr<Pango::Context> t_y_axis_label_ctxt = x_axis_label->get_context();
Pango::Matrix p_matrix;
// apply some transformation
p_matrix.xx = 0.0;
p_matrix.xy = 1.0;
p_matrix.yx = 1.0;
p_matrix.yy = 0.0;
p_matrix.x0 = 0.0;
p_matrix.y0 = 0.0;
t_y_axis_label_ctxt->set_matrix(p_matrix);
Glib::RefPtr<Pango::Layout> y_axis_label = Pango::Layout::create(t_y_axis_label_ctxt);
y_axis_label->set_text("y-axis label"); // if this line of code is omitted I would expect, at least the text "x-axis label" to be rendered. But this does not happen.
y_axis_label->set_font_description(font);
cr->move_to(0.0,0.0);
y_axis_label->show_in_cairo_context(cr); // renders no output
cr->restore();
我怀疑这个问题与我从 x 轴标签检索的上下文有关,并且预期的复制行为没有表现出来。