javascript – gjs cairo上下文绘图不在杂乱窗口中显示

我正在尝试使用javascript绑定将一个简单的开罗绘图绘制到一个混乱的窗口.我的问题是,除了命名略有不同的函数的一半,无论我尝试什么,都没有显示开罗绘图.我使用了python的一个例子,它可以工作,并将它移植到javascript.我也在使用内省来获取Clutter模块实例.我也在使用gjs版本0.7.14.谁能告诉我出了什么问题.

下面是我正在使用的示例代码.

const cairo = imports.cairo;
const clutter =  imports.gi.Clutter;

function on_button_press_event (stage,event) {
    clutter.main_quit();
}

function draw(cairo_tex) {
    var context = cairo_tex.create();


    context.scale(200,200);
    context.setLineWidth(0.1);
    var colour2 = new clutter.Color();
    colour2.from_string('#dd000088');
    clutter.cairo_set_source_color(context,colour2);
    context.translate(0.5,0.5);
    context.arc(0,0.4,Math.PI * 2);
    context.stroke();
}

function main () {
    clutter.init(0,null);
    var stage = new clutter.Stage();
    var colour = new clutter.Color();
    colour.from_string("#ffccccff");
    stage.set_color(colour);
    stage.set_size(400,300);
    stage.connect('button-press-event',on_button_press_event);
    stage.connect('destroy',clutter.main_quit);

    var cairo_tex = new clutter.CairoTexture.new(200,200);
    cairo_tex.set_position((stage.get_width() - 200) / 2,(stage.get_height() - 200) / 2);

    draw(cairo_tex);


    var center_x = cairo_tex.get_width() / 2;
    var center_z = cairo_tex.get_height() / 2;
    cairo_tex.set_rotation(clutter.AlignAxis.Y_AXIS,45.0,center_x,center_z);
    stage.add_actor(cairo_tex);
    cairo_tex.show();

    stage.show();

    clutter.main();
}

main();

我认为这不起作用的原因与删除javascript中的cairo上下文有关. context.destroy不存在,并且使用delete也不存在.事实上如果我使用删除然后我收到警告

WARNING: 'applying the 'delete' operator to an unqualified name is deprecated'

这根本没有用.根据参与gjs的一些开发人员发布的内容,分配给null应该具有相同的效果,因为它被垃圾收集.我怀疑幕后是否有任何东西需要收集.

如果有人可以说这是否属实,那么我会接受这个作为答案.

更新：

我已将问题区域缩小到imports.gi.Clutter.我尝试了另一个例子,但这次使用Gtk而不是Clutter,以下代码实际上有效

cairo = imports.cairo;
Gtk = imports.gi.Gtk;
Gdk = imports.gi.Gdk;

function draw_arc(drawing_area){
    var cr = Gdk.cairo_create(drawing_area.get_window());

    cr.scale(2,2);

    cr.operator = cairo.Operator.CLEAR;
    cr.paint();
    cr.operator = cairo.Operator.OVER;

    cr.setSourceRGB(0,255,0);
    cr.arc(128,128,76.8,2*Math.PI);
    cr.fill();

    return false;
}

Gtk.init(0,null);

var w = new Gtk.Window();
w.connect('delete-event',Gtk.main_quit);

var d = new Gtk.DrawingArea();
w.add(d);

w.resize(500,600);
w.decorated = false;

d.connect('draw',draw_arc);

w.show_all();
Gtk.main();

这让我相信问题不在于cairo的gjs实现,而在于Clutter Cairo实现的gjs内省方法.我认为clutter.CairoTexture.new或clutter.CairoTexture.create没有正确实现.我怀疑它是导致问题的clutter.CairoTexture.create.

最佳答案

使用Clutter和Cairo之间的新集成,特别是Clutter.Canvas,这将在屏幕上绘制一个圆圈：

const Clutter = imports.gi.Clutter;
const Cairo = imports.cairo;

const draw_stuff = function (canvas,cr,width,height) {
    cr.save ();
    cr.setOperator (Cairo.Operator.CLEAR);
    cr.paint ();
    cr.restore ();
    cr.setOperator (Cairo.Operator.OVER);
    cr.scale (width,height);
    cr.setLineCap (Cairo.LineCap.ROUND);
    cr.setLineWidth (0.1);

    cr.translate (0.5,0.5);
    cr.arc (0,Math.PI * 2);
    cr.stroke ();

    return true;
};

const test = function () {
    Clutter.init(null);

    let stage = new Clutter.Stage();
    stage.set_title ("Circle!");

    let color = new Clutter.Color({
        red : 255,green : 0,blue : 0,alpha : 128 // Just for the heck of it.
});
stage.set_background_color(color);
stage.set_size(300,300);

let canvas = new Clutter.Canvas ();
canvas.set_size (155,155);

let dummy = new Clutter.Actor ();
dummy.set_content (canvas);
dummy.set_size(155,155);
stage.add_child (dummy);

stage.connect ("destroy",Clutter.main_quit);
canvas.connect ("draw",draw_stuff);
canvas.invalidate ();
stage.show_all();

Clutter.main ();
};

test ();

javascript – gjs cairo上下文绘图不在杂乱窗口中显示

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