Add setup_contrast_popup!

This allows non-AbstractArrays to exploit the contrast GUI.

Author: timholy

Project.toml

@@ -1,7 +1,7 @@
 name = "ImageView"
 uuid = "86fae568-95e7-573e-a6b2-d8a6b900c9ef"
 author = ["Tim Holy <tim.holy@gmail.com", "Jared Wahlstrand <jwahlstrand@gmail.com>"]
-version = "0.13.0"
+version = "0.13.1"
 
 [deps]
 AxisArrays = "39de3d68-74b9-583c-8d2d-e117c070f3a9"

src/ImageView.jl

@@ -18,7 +18,7 @@ using Compat # for @constprop :none
 export AnnotationText, AnnotationPoint, AnnotationPoints,
        AnnotationLine, AnnotationLines, AnnotationBox
 export CLim, annotate!, annotations, canvasgrid, imshow, imshow!, imshow_gui, imlink,
-       roi, scalebar, slice2d
+       roi, scalebar, setup_contrast_popup!, slice2d
 
 const AbstractGray{T} = Color{T,1}
 const GrayLike = Union{AbstractGray,Number}
@@ -733,6 +733,47 @@ function create_contrast_popup(canvas, enabled, hists, clim)
     end
 end
 
+function dummy_histsig(clim::Observable{CLim{T}}) where {T<:GrayLike}
+    Th = float(T)
+    cl = clim[]
+    lo, hi = Th(cl.min), Th(cl.max)
+    if !(lo < hi)
+        lo, hi = zero(Th), one(Th)
+    end
+    span = hi - lo
+    rng = LinRange(lo - span/2, hi + span/2, 300)
+    Observable(Histogram(rng, zeros(Int, 299), :right, false))
+end
+
+dummy_histsigs(clim::Observable{CLim{T}}) where {T<:GrayLike} =
+    [dummy_histsig(clim)]
+
+dummy_histsigs(clim::Observable{CLim{T}}) where {T<:AbstractRGB} =
+    [dummy_histsig(map(x->channel_clim(red, x), clim)),
+     dummy_histsig(map(x->channel_clim(green, x), clim)),
+     dummy_histsig(map(x->channel_clim(blue, x), clim))]
+
+"""
+    setup_contrast_popup!(canvas, clim; img=nothing)
+
+Set up a right-click context menu on `canvas` that allows interactive
+adjustment of `clim` via a contrast GUI window. If `img` is an
+`Observable` wrapping an array compatible with `clim`, a histogram of
+pixel intensities is computed and shown whenever the GUI is opened.
+Without `img`, the GUI shows sliders only (no histogram).
+
+This is a lower-level complement to [`imshow`](@ref), useful when
+contrast is managed internally by the image type but an interactive
+right-click popup is still desired.
+"""
+function setup_contrast_popup!(canvas, clim::Observable{CLim{T}};
+                                img::Union{Nothing,Observable}=nothing) where T
+    enabled = Observable(false)
+    histsigs = img === nothing ? dummy_histsigs(clim) : histsignals(enabled, img, clim)
+    push!(canvas.preserved, create_contrast_popup(canvas, enabled, histsigs, clim))
+    return canvas
+end
+
 function map_image_roi(@nospecialize(img), zr::Observable{ZoomRegion{T}}, slices...) where T
     map(zr, slices...) do r, s...
         cv = r.currentview

test/contrast.jl

@@ -1,5 +1,6 @@
 using ImageView, ImageCore, ImageView.Observables, MultiChannelColors
 using Gtk4: Gtk4
+using GtkObservables: GtkObservables
 using Test
 
 @testset "contrast GUI" begin
@@ -32,3 +33,53 @@ using Test
         @test_broken sum(h.weights) > 0
     end
 end
+
+@testset "setup_contrast_popup!" begin
+    # dummy_histsig: range is [lo-span/2, hi+span/2] with zero counts
+    clim = Observable(CLim(0.2f0, 0.8f0))
+    hsig = ImageView.dummy_histsig(clim)
+    h = hsig[]
+    @test all(iszero, h.weights)
+    @test length(h.weights) == 299         # 300-point LinRange → 299 bins
+    @test first(h.edges[1]) ≈ -0.1f0       # 0.2 - 0.6/2
+    @test last(h.edges[1])  ≈  1.1f0       # 0.8 + 0.6/2
+
+    # histogram range updates reactively when clim changes
+    clim[] = CLim(0.0f0, 0.5f0)
+    h2 = hsig[]
+    @test first(h2.edges[1]) ≈ -0.25f0     # 0.0 - 0.5/2
+    @test last(h2.edges[1])  ≈  0.75f0     # 0.5 + 0.5/2
+
+    # degenerate CLim (min == max) falls back to [0,1]-based range
+    hsig_degen = ImageView.dummy_histsig(Observable(CLim(0.5f0, 0.5f0)))
+    h_degen = hsig_degen[]
+    @test first(h_degen.edges[1]) ≈ -0.5f0  # 0 - 1/2
+    @test last(h_degen.edges[1])  ≈  1.5f0  # 1 + 1/2
+
+    # dummy_histsigs: 1 signal for GrayLike, 3 for AbstractRGB
+    @test length(ImageView.dummy_histsigs(Observable(CLim(0.0f0, 1.0f0)))) == 1
+    @test length(ImageView.dummy_histsigs(
+        Observable(CLim(RGB(0f0,0f0,0f0), RGB(1f0,1f0,1f0))))) == 3
+
+    # setup_contrast_popup! registers the contrast_gui action on the canvas
+    # (gridsize (1,1) default → gd["canvas"] is a single Canvas, not a matrix)
+    gd = imshow_gui((50, 50))
+    canvas = gd["canvas"]
+    clim2 = Observable(CLim(0.0f0, 1.0f0))
+    n_preserved = length(canvas.preserved)
+    ret = setup_contrast_popup!(canvas, clim2)
+    @test ret === canvas                                 # returns the canvas
+    @test "contrast_gui" in keys(canvas.action_group)
+    @test length(canvas.preserved) > n_preserved         # callback was preserved
+
+    # with img kwarg: uses histsignals; action still registered
+    gd2 = imshow_gui((50, 50))
+    canvas2 = gd2["canvas"]
+    clim3 = Observable(CLim(0.0f0, 1.0f0))
+    img  = Observable(rand(Float32, 10, 10))
+    setup_contrast_popup!(canvas2, clim3; img=img)
+    @test "contrast_gui" in keys(canvas2.action_group)
+
+    Gtk4.destroy(gd["window"])
+    Gtk4.destroy(gd2["window"])
+end